Most puzzling (and wastefully expensive) car problem ever.

[cotjones 10+ year member]

K question...

The manual says to check the fuel pressure, use a T-fitting.

My friend didn't.

He simply disconnected the fuel line from the inlet, and put the gauge on it, then we turned the ignition to on, and even tried to crank it a little.

Would that still give an accurate reading or do you HAVE to use the T-fitting?

 

[VWBobby 10+ year member]

Yes you HAVE to have the Tee fitting. This makes it so you can measure the pressure of the fuel rail while the engine is running and to also check for leaking injector(s) with the ignition turned off. The pressure will drop slowly if you have a leaking injector with the fuel pump running. If you are checking for a leaking regulator, you leave the engine and the pump off and measure the standing fuel pressure in the rail.

 

[cotjones 10+ year member]

But shouldn't it build pressure even without the T, (with the fuel line capped). when the ignition is set to "on" (not started?)

With the fuel in connected straight into the meter we never saw above 4 or 5 psi.

regardless of the injectors, regulator, and return and junk,

Wouldn't the lack of pressure on the inlet isolate the problem to the fuel line-in (ie: fuel pump, filter, etc.)

or is there some kind of pressure release valve that would prevent pressure from building with the line capped like that?

 

[Wingman0121 10+ year member]

Heh you think that's expensive, look up "northstar V8 blown headgasket", price starts at $2000.

I don't know anything about the S-dime but can a clogged catalytic converter add to the problem?

 

[bigbangtheory 5,000+ posts]

Just an idea, maybe fix the exhaust leak? //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

 

[cotjones 10+ year member]

Just an idea, maybe fix the exhaust leak? //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

well...

#1 I did, no change

#2 I already tried disconnecting the O2 to check that that wasn't the problem

#3 it's had an exhaust leak for at least the last 10 years.

 

[VWBobby 10+ year member]

But shouldn't it build pressure even without the T, (with the fuel line capped). when the ignition is set to "on" (not started?)
With the fuel in connected straight into the meter we never saw above 4 or 5 psi.

If the line coming directly from the pump was plugged into the meter, that will show you the pump isn't making more than 4-5 PSI....Its shot. If you plugged it into the return line coming from the rail, that's not good. It will show you that you either have a leaking injector, regulator or bad pump....since any one of those can cause a major pressure drop in the rail/line. //content.invisioncic.com/y282845/emoticons/smile.gif.1ebc41e1811405b213edfc4622c41e27.gif

Hope this helps!

Get the ~$20 HF fuel pressure gauge kit and tee it into your fuel rail at the feed side... You'll have a really good idea of what's failing once you do this and its cheap and useful to have in the toolbox. //content.invisioncic.com/y282845/emoticons/wink.gif.608e3ea05f1a9f98611af0861652f8fb.gif

 

[jonny101abc 10+ year member]

sounds like the computer is going into auto shut down mode

happens to Chevy's and dodge's

get the ECU re flashed or replace the eprom

 

[audioatg 10+ year member]

sounds like the computer is going into auto shut down mode
happens to Chevy's and dodge's

get the ECU re flashed or replace the eprom

I think your a tad bit off for the year of the vehicle. Just a bit.

 

[audioatg 10+ year member]

Like a said. Check fuel pressure. Now that have done it half way. I would still T into the line. Check running pressure like ppl have said. Then after doing that. Leave it hooked up. Turn the key off. Then watch the pressure. On your car you can watch the Injectors to see if they have a leak. They are right on top of the TBI.

How many miles do you have on the truck. Do you know If the fuel pump has ever been replaced.

 

[cotjones 10+ year member]

Like a said. Check fuel pressure. Now that have done it half way. I would still T into the line. Check running pressure like ppl have said. Then after doing that. Leave it hooked up. Turn the key off. Then watch the pressure. On your car you can watch the Injectors to see if they have a leak. They are right on top of the TBI.
How many miles do you have on the truck. Do you know If the fuel pump has ever been replaced.

There are about 160,000 miles on it. Not sure if its been replaced, its inherited. And been driven by alot of members of my family, so hard to tell. Injectors aren't leaky, i've rebuilt the TBI unit. I'm pretty sure not since fuel pressure was measured closed at the TB inlet as being bad, and my fuel filter is new, I have a bad pump.

But to make sure, the dealership offered to give me 2 free hours of diagnostics since they charged me 300$ to tell me to get 400$ in unnecessary repairs.

...How nice of them ::rolleyes

 

[bubbagumper6 5,000+ posts]

There are about 160,000 miles on it. Not sure if its been replaced, its inherited. And been driven by alot of members of my family, so hard to tell. Injectors aren't leaky, i've rebuilt the TBI unit. I'm pretty sure not since fuel pressure was measured closed at the TB inlet as being bad, and my fuel filter is new, I have a bad pump.
But to make sure, the dealership offered to give me 2 free hours of diagnostics since they charged me 300$ to tell me to get 400$ in unnecessary repairs.

...How nice of them ::rolleyes

What did you expect? You took your out of warranty car to the dealership, of course they're going to charge you out the ass. My local dealership won't even look at my car without first collecting $100.

 

[cotjones 10+ year member]

I think your a tad bit off for the year of the vehicle. Just a bit.

Giggle.

BTW no one knows whether the pressure fuel pressure should build with the fuel in line fed into the gauge instead of T'ed?

 

[cotjones 10+ year member]

AWESOME UPDATE. IT was the fuel pump, replaced it works almost perfectly now. Except there is still a small issue.

Acceleration and all that are pretty much back to normal, and it even idles well now but i'm seeing something odd happen, pretty sure its one of the sensors.

When you first crank it up, it starts relatively easily, but then idles very low and rough. It does this for about 2 minutes, then the roughness ceases, it revs up to 3K rpms, and slowly drops back down to a normal idle. Hmmm?