98 GMC Z-71
Question:
Big surprise, after new fuel truck will start, but misses still and sputters. —
– Hide quoted text — Show quoted text -> I have a 98 Z-71 with 5700 V-8 and yesterday it started hard, after sitting > for only about 2 hours after a 30 mile drive, temp was about 10. It also > missed for about 2 miles, then it was fine, but service engine light was on > the whole time, did the gas cap thing and nothing. Started it about 10 times > and it started fine. But service engine light still on. This morning after > being parked in a heated shop all nite, it would not start, had it towed to > dealer, just got off the phone with them and it started right up for them, > with no miss, runs fine, checked computer, NO CODES, how can this be?? the > engine light was on for a good 10 minutes. Called the guy who towed it, and > I asked him if he unhooked the battery, and a smart ass tone he says why > would I unhook the battery. Hell I dont know. They have checked fuel > pressure and voltage and everything is normal. I keep the tank 1/2 full, a > can of dry gas at every tank. My question is, how can there be no computer > codes?? Do they just disappear. Truck has 25,000 on it and it cant be froze > up cause it was at 55 degrees in the shop all night long, about 12 hours. It > shouldn’t be water, but could it be??? Dealer is still checking it to > things but is running out of ideas. He said were gonna keep it outside > tonite and see what happens, then I tell him I had it inside all nite last > —
Response:
Dealer claims air in the "popit" valve, dont know if thats correct spelling. The truck will be delivered to me this afternoon, I guess we well see. Any one ever hear of this?? Andy —
– Hide quoted text — Show quoted text -> I have a 98 Z-71 with 5700 V-8 and yesterday it started hard, after sitting > for only about 2 hours after a 30 mile drive, temp was about 10. It also > missed for about 2 miles, then it was fine, but service engine light was on > the whole time, did the gas cap thing and nothing. Started it about 10 times > and it started fine. But service engine light still on. This morning after > being parked in a heated shop all nite, it would not start, had it towed to > dealer, just got off the phone with them and it started right up for them, > with no miss, runs fine, checked computer, NO CODES, how can this be?? the > engine light was on for a good 10 minutes. Called the guy who towed it, and > I asked him if he unhooked the battery, and a smart ass tone he says why > would I unhook the battery. Hell I dont know. They have checked fuel > pressure and voltage and everything is normal. I keep the tank 1/2 full, a > can of dry gas at every tank. My question is, how can there be no computer > codes?? Do they just disappear. Truck has 25,000 on it and it cant be froze > up cause it was at 55 degrees in the shop all night long, about 12 hours. It > shouldn’t be water, but could it be??? Dealer is still checking it to > things but is running out of ideas. He said were gonna keep it outside > tonite and see what happens, then I tell him I had it inside all nite last > —
Response:
a full tank, and put new in. Said it started, but was sluggish, and we are gonna see what happens in the morning. —
– Hide quoted text — Show quoted text -> Called dealership this morning. I had him explain again what he did. This > time he says that GM told them to block the return line, creating excess > pressure, this causes the pop out relief valves in the pump to open, once > pressure is normal, valves close. I asked and what was the point of this?? > He couldn’t give me an answer, he said that GM told them to do it, so they > did. Ok new question, could one of these relief valves be stuck partially > open, thus reducing fuel pressure, or could it be a blockage in the fuel > line that is creating too much pressure and opening relief valve?? The > dealership doesn’t have a clue as to whats wrong with my truck, and they > won’t test the injector pressure because it involves too much work. Thanks > again. > — > >Ok dealership call at 9 this morning, your truck is done whenever you > want > >to come get it, ok what did you do to it, well like we told you yesterday > we > >thought an injector was bad, so we tested injector pressure and it was > fine, > >so we call GM. GM tells us to pinch off the return line so it creates > excess > >pressure at the back of the pump and the pump will reset its self. Ok I > say, > >sounds like a load of BS but it runs like it is supposed to right. YEP > runs > >good starts good, shouldn’t have any more trouble with it. Ok ill be down > >later. Got down there at 3 after an hour drive, crank and crank and > crank, > >wont start if it had to. What is the RESETTING the pump stuff, first I > have > >ever heard of it. Can some one explain this to me??? Please!! > I’ve worked for GM for going on 13 years, and I never heard of > "resetting" the pump. You pinch off the return line to check the > maximum output of the fuel pump. > If the fuel pressure on this engine is even 2 or 3 pounds low, it > either won’t run or will run like shit. That is…if the spec is 45 > psi(just grabbing #’s here, not sure off the top of my head)then at > about 42 or 41 psi the thing won’t run, or will run bad. I’ll see if > I can find a spec here at the house and post it later(snowed in and > bored 
). > >Also they gave we a 2000 GMC ext. cab 4×4 to drive, I like the ride, and > >firm option, but am not impressed with the interior styling. Just my > >thoughts. > >Thanks again > >Andy > >– > >> I have a 98 Z-71 with 5700 V-8 and yesterday it started hard, after > >sitting > >> for only about 2 hours after a 30 mile drive, temp was about 10. It > also > >> missed for about 2 miles, then it was fine, but service engine light > was > >on > >> the whole time, did the gas cap thing and nothing. Started it about 10 > >times > >> and it started fine. But service engine light still on. This morning > after > >> being parked in a heated shop all nite, it would not start, had it > towed > >to > >> dealer, just got off the phone with them and it started right up for > them, > >> with no miss, runs fine, checked computer, NO CODES, how can this be?? > the > >> engine light was on for a good 10 minutes. Called the guy who towed it, > >and > >> I asked him if he unhooked the battery, and a smart ass tone he says > why > >> would I unhook the battery. Hell I dont know. They have checked fuel > >> pressure and voltage and everything is normal. I keep the tank 1/2 > full, a > >> can of dry gas at every tank. My question is, how can there be no > computer > >> codes?? Do they just disappear. Truck has 25,000 on it and it cant be > >froze > >> up cause it was at 55 degrees in the shop all night long, about 12 > hours. > >It > >> shouldn’t be water, but could it be??? Dealer is still checking it to > >> things but is running out of ideas. He said were gonna keep it outside > >> tonite and see what happens, then I tell him I had it inside all nite > last > >> — > Big Daddy > ICQ#6342575 > ASE Master Auto Technition > Chevrolet Certified Master Tech.
Response:
>Called dealership this morning. I had him explain again what he did. This >time he says that GM told them to block the return line, creating excess >pressure, this causes the pop out relief valves in the pump to open, once >pressure is normal, valves close. I asked and what was the point of this?? >He couldn’t give me an answer, he said that GM told them to do it, so they >did. Ok new question, could one of these relief valves be stuck partially >open, thus reducing fuel pressure, or could it be a blockage in the fuel >line that is creating too much pressure and opening relief valve?? The >dealership doesn’t have a clue as to whats wrong with my truck, and they >won’t test the injector pressure because it involves too much work. Thanks >again.
They’re right about the amount of work involved in testing the fuel pressure. I wonder why GM didn’t put test ports on the lines, I know it probably would have cost about 35cents, but sure would have made the tech’s life easier. Still, that’s no excuse for not testing the pressure when the complaint warrants it. I’d find another dealer if at all possible. Big Daddy ICQ#6342575 ASE Master Auto Technition Chevrolet Certified Master Tech.
Response:
Called dealership this morning. I had him explain again what he did. This time he says that GM told them to block the return line, creating excess pressure, this causes the pop out relief valves in the pump to open, once pressure is normal, valves close. I asked and what was the point of this?? He couldn’t give me an answer, he said that GM told them to do it, so they did. Ok new question, could one of these relief valves be stuck partially open, thus reducing fuel pressure, or could it be a blockage in the fuel line that is creating too much pressure and opening relief valve?? The dealership doesn’t have a clue as to whats wrong with my truck, and they won’t test the injector pressure because it involves too much work. Thanks again. —
– Hide quoted text — Show quoted text ->Ok dealership call at 9 this morning, your truck is done whenever you want >to come get it, ok what did you do to it, well like we told you yesterday we >thought an injector was bad, so we tested injector pressure and it was fine, >so we call GM. GM tells us to pinch off the return line so it creates excess >pressure at the back of the pump and the pump will reset its self. Ok I say, >sounds like a load of BS but it runs like it is supposed to right. YEP runs >good starts good, shouldn’t have any more trouble with it. Ok ill be down >later. Got down there at 3 after an hour drive, crank and crank and crank, >wont start if it had to. What is the RESETTING the pump stuff, first I have >ever heard of it. Can some one explain this to me??? Please!! > I’ve worked for GM for going on 13 years, and I never heard of > "resetting" the pump. You pinch off the return line to check the > maximum output of the fuel pump. > If the fuel pressure on this engine is even 2 or 3 pounds low, it > either won’t run or will run like shit. That is…if the spec is 45 > psi(just grabbing #’s here, not sure off the top of my head)then at > about 42 or 41 psi the thing won’t run, or will run bad. I’ll see if > I can find a spec here at the house and post it later(snowed in and > bored ). >Also they gave we a 2000 GMC ext. cab 4×4 to drive, I like the ride, and >firm option, but am not impressed with the interior styling. Just my >thoughts. >Thanks again >Andy >– >> I have a 98 Z-71 with 5700 V-8 and yesterday it started hard, after >sitting >> for only about 2 hours after a 30 mile drive, temp was about 10. It also >> missed for about 2 miles, then it was fine, but service engine light was >on >> the whole time, did the gas cap thing and nothing. Started it about 10 >times >> and it started fine. But service engine light still on. This morning after >> being parked in a heated shop all nite, it would not start, had it towed >to >> dealer, just got off the phone with them and it started right up for them, >> with no miss, runs fine, checked computer, NO CODES, how can this be?? the >> engine light was on for a good 10 minutes. Called the guy who towed it, >and >> I asked him if he unhooked the battery, and a smart ass tone he says why >> would I unhook the battery. Hell I dont know. They have checked fuel >> pressure and voltage and everything is normal. I keep the tank 1/2 full, a >> can of dry gas at every tank. My question is, how can there be no computer >> codes?? Do they just disappear. Truck has 25,000 on it and it cant be >froze >> up cause it was at 55 degrees in the shop all night long, about 12 hours. >It >> shouldn’t be water, but could it be??? Dealer is still checking it to >> things but is running out of ideas. He said were gonna keep it outside >> tonite and see what happens, then I tell him I had it inside all nite last >> — > Big Daddy > ICQ#6342575 > ASE Master Auto Technition > Chevrolet Certified Master Tech.
Response:
>Ok dealership call at 9 this morning, your truck is done whenever you want >to come get it, ok what did you do to it, well like we told you yesterday we >thought an injector was bad, so we tested injector pressure and it was fine, >so we call GM. GM tells us to pinch off the return line so it creates excess >pressure at the back of the pump and the pump will reset its self. Ok I say, >sounds like a load of BS but it runs like it is supposed to right. YEP runs >good starts good, shouldn’t have any more trouble with it. Ok ill be down >later. Got down there at 3 after an hour drive, crank and crank and crank, >wont start if it had to. What is the RESETTING the pump stuff, first I have >ever heard of it. Can some one explain this to me??? Please!!
I’ve worked for GM for going on 13 years, and I never heard of "resetting" the pump. You pinch off the return line to check the maximum output of the fuel pump. If the fuel pressure on this engine is even 2 or 3 pounds low, it either won’t run or will run like shit. That is…if the spec is 45 psi(just grabbing #’s here, not sure off the top of my head)then at about 42 or 41 psi the thing won’t run, or will run bad. I’ll see if I can find a spec here at the house and post it later(snowed in and bored ). – Hide quoted text — Show quoted text ->Also they gave we a 2000 GMC ext. cab 4×4 to drive, I like the ride, and >firm option, but am not impressed with the interior styling. Just my >thoughts. >Thanks again >Andy >– > I have a 98 Z-71 with 5700 V-8 and yesterday it started hard, after >sitting > for only about 2 hours after a 30 mile drive, temp was about 10. It also > missed for about 2 miles, then it was fine, but service engine light was >on > the whole time, did the gas cap thing and nothing. Started it about 10 >times > and it started fine. But service engine light still on. This morning after > being parked in a heated shop all nite, it would not start, had it towed >to > dealer, just got off the phone with them and it started right up for them, > with no miss, runs fine, checked computer, NO CODES, how can this be?? the > engine light was on for a good 10 minutes. Called the guy who towed it, >and > I asked him if he unhooked the battery, and a smart ass tone he says why > would I unhook the battery. Hell I dont know. They have checked fuel > pressure and voltage and everything is normal. I keep the tank 1/2 full, a > can of dry gas at every tank. My question is, how can there be no computer > codes?? Do they just disappear. Truck has 25,000 on it and it cant be >froze > up cause it was at 55 degrees in the shop all night long, about 12 hours. >It > shouldn’t be water, but could it be??? Dealer is still checking it to > things but is running out of ideas. He said were gonna keep it outside > tonite and see what happens, then I tell him I had it inside all nite last > —
Big Daddy ICQ#6342575 ASE Master Auto Technition Chevrolet Certified Master Tech.
Response:
>Dealership has checked every thing but injector pressure, and they said they >wouldn’t do that until it acted up again. New question, is there a check >valve between the throttle body, and tank, like in the fuel filter?? My >theory is that the fuel is draining back to tank, or pump is loosing prime, >and it starts after cranking the piss out of it. Dealer drove it around >today, he said it started and that’s all he would say about it, but said it >ran fine when they drove it.
Try a fuel pump relay, they can cause an extended crank time in a cold engine. Big Daddy ICQ#6342575 ASE Master Auto Technition Chevrolet Certified Master Tech. Shop Foreman; John Walters Chevrolet Conway, Arkansas.
Response:
Ok dealership call at 9 this morning, your truck is done whenever you want to come get it, ok what did you do to it, well like we told you yesterday we thought an injector was bad, so we tested injector pressure and it was fine, so we call GM. GM tells us to pinch off the return line so it creates excess pressure at the back of the pump and the pump will reset its self. Ok I say, sounds like a load of BS but it runs like it is supposed to right. YEP runs good starts good, shouldn’t have any more trouble with it. Ok ill be down later. Got down there at 3 after an hour drive, crank and crank and crank, wont start if it had to. What is the RESETTING the pump stuff, first I have ever heard of it. Can some one explain this to me??? Please!! Also they gave we a 2000 GMC ext. cab 4×4 to drive, I like the ride, and firm option, but am not impressed with the interior styling. Just my thoughts. Thanks again Andy —
– Hide quoted text — Show quoted text -> I have a 98 Z-71 with 5700 V-8 and yesterday it started hard, after sitting > for only about 2 hours after a 30 mile drive, temp was about 10. It also > missed for about 2 miles, then it was fine, but service engine light was on > the whole time, did the gas cap thing and nothing. Started it about 10 times > and it started fine. But service engine light still on. This morning after > being parked in a heated shop all nite, it would not start, had it towed to > dealer, just got off the phone with them and it started right up for them, > with no miss, runs fine, checked computer, NO CODES, how can this be?? the > engine light was on for a good 10 minutes. Called the guy who towed it, and > I asked him if he unhooked the battery, and a smart ass tone he says why > would I unhook the battery. Hell I dont know. They have checked fuel > pressure and voltage and everything is normal. I keep the tank 1/2 full, a > can of dry gas at every tank. My question is, how can there be no computer > codes?? Do they just disappear. Truck has 25,000 on it and it cant be froze > up cause it was at 55 degrees in the shop all night long, about 12 hours. It > shouldn’t be water, but could it be??? Dealer is still checking it to > things but is running out of ideas. He said were gonna keep it outside > tonite and see what happens, then I tell him I had it inside all nite last > —
Response:
Truck started after sitting outside last nite. However it did not start when it sat in the heated shop the previous nite.
– Hide quoted text — Show quoted text ->Dealership has checked every thing but injector pressure, and they said they >wouldn’t do that until it acted up again. New question, is there a check >valve between the throttle body, and tank, like in the fuel filter?? My >theory is that the fuel is draining back to tank, or pump is loosing prime, >and it starts after cranking the piss out of it. Dealer drove it around >today, he said it started and that’s all he would say about it, but said it >ran fine when they drove it. > Try a fuel pump relay, they can cause an extended crank time in a cold > engine. > Big Daddy > ICQ#6342575 > ASE Master Auto Technition > Chevrolet Certified Master Tech. > Shop Foreman; John Walters Chevrolet > Conway, Arkansas.
Response:
Dealership has checked every thing but injector pressure, and they said they wouldn’t do that until it acted up again. New question, is there a check valve between the throttle body, and tank, like in the fuel filter?? My theory is that the fuel is draining back to tank, or pump is loosing prime, and it starts after cranking the piss out of it. Dealer drove it around today, he said it started and that’s all he would say about it, but said it ran fine when they drove it. —
– Hide quoted text — Show quoted text -> I have a 98 Z-71 with 5700 V-8 and yesterday it started hard, after sitting > for only about 2 hours after a 30 mile drive, temp was about 10. It also > missed for about 2 miles, then it was fine, but service engine light was on > the whole time, did the gas cap thing and nothing. Started it about 10 times > and it started fine. But service engine light still on. This morning after > being parked in a heated shop all nite, it would not start, had it towed to > dealer, just got off the phone with them and it started right up for them, > with no miss, runs fine, checked computer, NO CODES, how can this be?? the > engine light was on for a good 10 minutes. Called the guy who towed it, and > I asked him if he unhooked the battery, and a smart ass tone he says why > would I unhook the battery. Hell I dont know. They have checked fuel > pressure and voltage and everything is normal. I keep the tank 1/2 full, a > can of dry gas at every tank. My question is, how can there be no computer > codes?? Do they just disappear. Truck has 25,000 on it and it cant be froze > up cause it was at 55 degrees in the shop all night long, about 12 hours. It > shouldn’t be water, but could it be??? Dealer is still checking it to > things but is running out of ideas. He said were gonna keep it outside > tonite and see what happens, then I tell him I had it inside all nite last > —
Response:
Check your spark plugs and spark plug wires. You may have a bad wire or plug. There was a post here about a 94 with a skipping prob and was finally a wire. You say it wouldn’t start…..did it turn over or was it completely dead like nothing happened at all?? —
– Hide quoted text — Show quoted text -> I have a 98 Z-71 with 5700 V-8 and yesterday it started hard, after sitting > for only about 2 hours after a 30 mile drive, temp was about 10. It also > missed for about 2 miles, then it was fine, but service engine light was on > the whole time, did the gas cap thing and nothing. Started it about 10 times > and it started fine. But service engine light still on. This morning after > being parked in a heated shop all nite, it would not start, had it towed to > dealer, just got off the phone with them and it started right up for them, > with no miss, runs fine, checked computer, NO CODES, how can this be?? the > engine light was on for a good 10 minutes. Called the guy who towed it, and > I asked him if he unhooked the battery, and a smart ass tone he says why > would I unhook the battery. Hell I dont know. They have checked fuel > pressure and voltage and everything is normal. I keep the tank 1/2 full, a > can of dry gas at every tank. My question is, how can there be no computer > codes?? Do they just disappear. Truck has 25,000 on it and it cant be froze > up cause it was at 55 degrees in the shop all night long, about 12 hours. It > shouldn’t be water, but could it be??? Dealer is still checking it to > things but is running out of ideas. He said were gonna keep it outside > tonite and see what happens, then I tell him I had it inside all nite last > —
Response:
I have a 98 Z-71 with 5700 V-8 and yesterday it started hard, after sitting for only about 2 hours after a 30 mile drive, temp was about 10. It also missed for about 2 miles, then it was fine, but service engine light was on the whole time, did the gas cap thing and nothing. Started it about 10 times and it started fine. But service engine light still on. This morning after being parked in a heated shop all nite, it would not start, had it towed to dealer, just got off the phone with them and it started right up for them, with no miss, runs fine, checked computer, NO CODES, how can this be?? the engine light was on for a good 10 minutes. Called the guy who towed it, and I asked him if he unhooked the battery, and a smart ass tone he says why would I unhook the battery. Hell I dont know. They have checked fuel pressure and voltage and everything is normal. I keep the tank 1/2 full, a can of dry gas at every tank. My question is, how can there be no computer codes?? Do they just disappear. Truck has 25,000 on it and it cant be froze up cause it was at 55 degrees in the shop all night long, about 12 hours. It shouldn’t be water, but could it be??? Dealer is still checking it to things but is running out of ideas. He said were gonna keep it outside tonite and see what happens, then I tell him I had it inside all nite last —
