truck starts when gas pedal push to the floor then stalls after he releases his foot

70

Asked by Aug 22, 2015 at 08:47 PM about the 1998 GMC Sierra 1500

Question type: Maintenance & Repair

my grampa bought his 1998 gmc sierra 1500 sle  2 weeks ago he has put new spark
plugs in the truck and has put a new fuel filter in the truck its still doing the same thing the
only thing we can think of it might be bad gas that he put in it from a gas station that sells
ethanol fuel if anyone has had this same problem please leave me a comment under this
post thank you it would mean alot to us also the engine in the truck is a vortec

11 Answers

56,775

Sounds like you Grandpa's truck has leaking fuel injectors. When he holds the accelerator pedal to the floor while cranking (starting) it this puts the computer in "clear flood mode". When in clear flood mode the amount of injector spray is greatly reduced to clear out the excess gasoline from the cylinders. Sounds like it's running way too rich (too much gasoline). Check the spark plugs, if they're wet with gasoline and/or have black fluffy deposits on the tips it's definitely running too rich. Check for faulty fuel injectors and inspect the air cleaner as well. If Grandpa's truck has the spider injector set up they're prone to failure. HTH. -Jim

70

thanks js08016 but we put bran new correct spark plugs in and changed the fuel filter

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70

but we already put brand new spark plugs and fuel filter

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70

and the weirdest thing is we put the brand new spark plugs in and the next day there shot again explain that to us

1 out of 1 people think this is helpful.
56,775

I checked and this truck has the "spider" injector set up. They're notorious for failure. It's probably dumping fuel. Have you checked the fuel pressure regulator? HTH. -Jim

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56,775

Are they all black? Or wet and smell like gasoline? If so it's definitely dumping fuel. HTH. -Jim

70

wheres is the fuel pressure regulator

2 out of 2 people think this is helpful.
56,775

It'll be on the fuel line on or near the top of the engine. It looks like a small round metal can with a vacuum hose connected to it. HTH. -Jim

1 out of 1 people think this is helpful.
56,775

From rockauto.com:

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70

ok thanks his son said he checked it but never tested it if thats what is i wanna thank you for ur help and if thats not it what else do u think it might be

2 out of 2 people think this is helpful.
56,775

You're welcome. Glad to help. If it's not the fuel pressure regulator then my next prime suspect is going to be that "spider" fuel injector assembly. If it turns out to be bad, don't replace the individual injectors. Replace the whole assembly and be sure it's the new, improved, design. The new design is much better.

2 out of 2 people think this is helpful.

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