92 Suburban ... AKA the disasterwagon

[shibbershabber]

Id call it the Mystery Machine... but that would be an insult to the original.

92 Suburban
TBI 350 about 150k miles


So Ive shotgunned this a little and have even begrudgingly taken it to the dealer...

Still... N O T H I N G ! ! ! This thing is making Fords look better and better each day it sits in front of my house refusing to cooperate.


Heres the problem.

Initially the idle would just go up and down very rhythmically and would do so for several minutes.

after many go rounds with other mechanics I took it to the dealer. They said the dizzy was shot (even though it was brand new (couple months) and timed correctly)
so out of frustration I let them put one in. It was fine for about two days.

THEN the up and down started again. I took it back to the dealer... they said it was fine.

Couple days after that, it died on the road gradually losing power until it stalled out. I had it towed back to the dealer.
they said that the fuel pump was shot. ( again, the entire assembly was replaced within the last 3k miles.) I did not agree with their assessment and brought the truck home.

There it sat while I tried to figure it out myself.
I tried to get it to start and it would sputter and backfire a lot. I got a CEL and a code for the EGR (which was also new) so I replaced the EGR solenoid and checked the wires.

Still sputtering and backfiring. No start.

I suspected the Oil Pressure Sensor & its wiring. This sensor is wired into the fuel pump circuit and the wires looked like hell. suspicious looking spliced and a lot of tape. So I got in and cut out the crap and spliced in good wire and proper connectors.

It fired up and ran just fine!!!!

For about two minutes. (maybe once the high idle stopped?)
and then it did the up and down, up and down until it died.


So here I am. With a truck that wont run, a brain out of ideas and a wallet without money. Three seperate mechanics + the dealer are lost on this thing.

I can see that while its running the spray pattern looks like crap. As it did before. Both sides were equally poor, spitting and dripping. NOW the pass side is dumping fuel and the driver side is barely putting anything out at all.
The injectors and harness have about 3k on them, brand new Delphis. I have since taken them out to inspect and clean. NO change.

What the hell is going on here?

 

[IOWNJUNK]

What does fuel filter look like? Seems like a lot of new fuel system parts to be performing so poorly, new everything but a crappy fuel pattern? That sounds like a bunch of trash in your tank/lines and its making you work hard.

Good luck man, we've all been there.

 

[shibbershabber]

What does fuel filter look like? Seems like a lot of new fuel system parts to be performing so poorly, new everything but a crappy fuel pattern? That sounds like a bunch of trash in your tank/lines and its making you work hard.

Good luck man, we've all been there.

Well a few thousand miles ago I replaced the pump and the inside of the tank was nice! I also replaced the fuel filter then.

Definitely no blockages

 

[thunderstruck]

What's your fuel pressure when it's idling?

Does it run any better with the ignition advance wire disconnected? It's a brown wire with a black stripe, I do not know where the disconnect is at on a 92 though.

 

[megaburb]

Park it in the woods for six months. Should fix itself lmao! Has it had the same tank of fuel this whole time?

94' GMC MEGABURB

 

[IOWNJUNK]

Did new distributor come with new control module? That was the biggest problem I had on any tbi engine. Most auto parts stores can test them.

If you still have crappy spray pattern you might try pulling the tbi off and cleaning/replacing.