1990 fuel injected GMC 6500 won’t start cold.

[4570Man]

So the title pretty much sums this one up. I’ve got a fuel injected topkick that won’t start cold. And the definition of cold is only like 50 degrees ambient temperature. If I spray brake cleaner down the intake it’ll start. Even if it only runs for 30 seconds and dies it’ll start back and all the rest of the starts that day it’ll start. Any ideas?

 

[xring100]

Is this a TBI i assume does it have a fuel pressure regulator?

I had a 96 4.3 that when it got cold bellow 30 it would not start not even attempt too. When ambient warmed up it was find. I found i had no spark i changed the cap and rotor it was fine never gave me a problem.

 

[4570Man]

Yes it’s TBI. I don’t know about the regulator. I’d assume since it fires the brake cleaner its fuel related not spark.

 

[ruffdog]

CK your fuel pressure from the pump.

 

[ultrarunner]

Mine had a bad relay... it was before I owned it.

Original owner said the only problem was it would not sometimes start... he had the fuel pump replaced and filters and the problem came back...

Then he said it turned out to be a bad relay... 1991 350ci

 

[4570Man]

I still haven’t done any troubleshooting on the case but it seems to start if you leave the key on for a minute or so. So option one is it’s pretending to be a diesel and making you wait for the glow plugs. The more likely option is there’s probably a anti drain back valve in the TBI and it’s not working and it takes a minute for it to get gas pumped back up there.

 

[Jstpssng]

Re: 1990 fuel injected GMC 6500 won稚 start cold.

^^^
Or the fuel pump's going, as somebody else already suggested. Leaving the key on gives it a chance to build up some pressure.
You should be able to get the pump pressure tested.