I am stumped w/ 1998 Chevy Suburban K1500https://www.scannerdanner.com/forum/pos

OK, ya’ll ready for this one?

2 years ago, it ran just fine, like always; parked it, then 2 months later went to use it and could not get it to start. Well, it would try to start, but only run about 1 second then die. My first thought was to check for spark and fuel, yes on the spark, fuel at 62 - 66 psi. went to google and it seemed like what I was experiencing was maybe an issue with the factory anti theft system. So down that rat hole. Frankly, my symptoms were not an exact match, but close enough I figured it as a possible. Eventually determined, (I think) that it was not the problem.

Then I had a stroke, so the rig sat for a looooong time. Started messing with again the last month and finally found the following:

Crank shaft position sensor had literally broken in 2,
And my fuel pump was now only producing 58 – 60 psi.

So replaced the sensor, got a new pump re-hung the tank last night, aaaaand NOTHING. Lol

It tried to start last night for almost 3 seconds, which was an improvement, but still won’t run.
Brand new pump only wants to bring it up to about 50 psi though, and that seemed wrong.
I had replaced the inline fuel filter when I dropped the tank.

So gave up last night and mixed a few drinks and muttered to myself.

Today, it sometimes will try for that 3 second run, and other times it just cranks with NO attempt to actually fire. Starting fluid SOMETIMES makes it try, but not consistently.

Today, it threw another problem or issue. If I use the fuel pump relay in place, the system will only come up to 50, maybe 52 psi; if I remove the relay and just jump the pins, it comes up to 60, maybe a titch more, but when I stop the jump, it falls back to 50 psi immediately.

Tried to get her to run with the charger on max boost, with starter fluid, NADA.

But I noticed that when I am jumping the relay or using the relay, there is now a sound of rushing water coming from that fuel injector electrical plug on the top of the intake manifold. WTH? And if I use the jump method, boy does it really sound like a stream! Cannot however, find any source of fuel on the ground. But if I go listen at the tank, pump is running merrily away, in jump, or only for couple seconds with the relay.

Oh yeah, fresh gas in the tank, so that is not the issue. And checked the cam shaft sensor also, it is fine. Amps on the jump is 9.5, and the pump has good ground and full voltage to it.

Just don’t know what the heck else to look at, and I MUST get this thing going, it is going to be my only car, lol, and there is a 20 mile walk to the nearest bus stop.

Thank you one and all for any ideas or help/advice. Oh yeah, forgot, the engine is 5.7 vortec. And one more thing, no codes showing at all.

Do you have a scanner?

How did you test/confirm that crank&cam sensors are good?

Can you measure the voltage drop over the relay contacts, load side? Oherwise for the sake of testing you may swap another relay in and check fuel pressure.

After sitting for two years there's a chance the injectors are gummed up/clogged. It's hard on these spider assemblies to test for pressure drop when the injectors open so you may want to pull the spider to check visually if the actually do inject.

Regarding the noise: make sure the pressure regulator is not stuck open and that the hose inside the plenum didn't come off. This would fill the plenum and cylinders with gas and could cause hydrolock! Check for gas in the oil /carter.

Thank you for your time and reply.

Yes, I have a scanner, maybe not a top of the line one, but it is pretty good I think, Actron 9580A.

I did find that the old fuel relay was in fact, burnt and replaced it.

I went thru testing of both cam and crank sensors following tutorials I found on the web. That was how I found out that the crank sensor was not working. But the cam had signal, power and ground.

Never heard that sound of flowing liquid before, lol, kind of wild, sounds about like a toilet refilling the tank.

I was kind of thinking that maybe I was going to have to go after the regulator, but was hoping someone would have a better idea.

Also, the new pump no longer will build up more than about 10 to 20 psi, but I assume that may be due to the sound of rushing fluid? If the system has effectively spring a leak, as it were, then it likely can't build up any real pressure. Or at least that is what I think.

Am I right in thinking that the only way for me to check that regulator is to take off the intake? Man am I gonna hate doing that, lol, old back injury is not gonna like being in that position. hahahahahahha

Thanks again, for your time, thoughts and questions to me.

This sounds like a stuck open regulator...

You can pinch/block off the return line to verify. One of the two lines entering the plenum on the "backside", close to the firewall, is the fuel feed line and the other one (smaller?) is the return. Not sure if you can access the return line in an other spot, close to the tank or fuel filter. Blocking off the return line pressure should go full gorilla, at least 80 to 100 psi.

It also might be a leaking check valve within the pump assembly. If fuel pressure stays low with the return line pinched off you may want to have a look there. Usually a bad check valve will not pull the pressure that low, so first suspect is still the regulator.

Thank you for your opinion.

At this point, I am kinda leaning towards the regulator and maybe the spider too. That new sound of rushing fluid, that just started up yesterday afternoon, and if the regulator and or the poppets are stuck open, that would explain, at least to me, the low to no pressure.

One thing still puzzles me though, and that is why does it come up to 60 psi if I jump the relay, but only 10 psi when the relay is in place. You can hear the difference in the sound of the river, lol, much much stronger flow rate if I jump it.

I will try the pinch off, try to see if I can come to a definite conclusion that the brand new pump is not bad.

Once I get in further, I will post results.

I would also say it's your fuel pressure regulator and it's under the top intake manifold. I would also upgrade to the new style fuel injectors while you are in there. The kit comes with a new regulator.