Fuel Delivery Issue

[tphilpot]

Hi Guys,

I have posted a couple of times about my sick Ty.

Lots of great advice has been given.

I have replaced & tested everything and now I am down to fuel delivery as the problem.

I have replaced the fuel pump & filter--problem still there. I have put a pressure guage on it and the Chilton manual is leading me to a leaking injector or a leaky pump coupling hose.

How do I test for each? I can't find the hose referred to in the manual that can be "pinched".

It also takes a while to start, which says to me that the pump is being compromized by something.

Help please. Borderline on parting the car out.

 

[WyoSyclone]

Re: Fuel Delivery Issue

You could take the feed line off of the fuel rail, plug the rail, get an adaptor and connect the fp gauge directly to the feed line. Energize the pump then turn it off. If it doesn't hold pressure then it's inside the tank. If it holds pressure it's probably a bad injector.

 

[Don W.]

Re: Fuel Delivery Issue

The hose they're referencing is probably the return. There IS a procedure in the manual. If someone doesn't beat me to it I'll post it tomorrow. (Manual at the shop) Using the procedure you can isolate if it's pump, regulator, or injectors. Unless you have an actual leak it's gonna be one of the three. If I were to bet it's the regulator. But don't quote me.

 

[The Bronze]

That's a good way. A good gauge would have a hose with the shut off valve in-line. It would make that test a 30 second ordeal. If you didn't want to plumb your rail and enjoy pulling spark plugs, you can let the car sit (I am assuming the fuel pressure was bleeding off after shutdown) until the fuel pressure has dropped to zero. Then disconnect the distributor (to keep the injectors from opening) and spin the engine over a few times and then pull the plugs. The wet plug is likely the leaker.

An even better idea is to pull the injectors and have them flow checked. They will clean them and check for leakage as well. You would then have a good idea of any injectors that are not flowing well or have a poor spray pattern. Lindertech is my recommendation. Cheap and saves your sanity when dealing with future driveability issues.

 

[Don W.]

Re: Fuel Delivery Issue

OK. The sequence is: (With fuel pressure gauge connected) turn on key, pump should run for about 2 secs, FP should be 38 +/-. Turn off key, does pressure hold?

If it doesn't hold then connect to firewall jumper (which runs the pump continuously) and gradually block PRESSURE line. Once blocked does pressure hold? If yes then you have a leak or pump ch valve is bad. No? Then repeat, blocking RETURN line. Did pressure hold? Yes: regulator is bad. No: leaky inj(s) somewhere.

Let us know what you find.

HTH

 

[tphilpot]

Re: Fuel Delivery Issue

Thanks for that. The Regulator is new and the fuel pump is new (although I put it in and could have screwed it up).

Pressure drops from 38 to 8 as soon as pump stops.

Another dumb question, where are the injectors? How easy/hard are they to get to?

For the life of me I can't locate a "hose" in the fuel line. Is it tucked somewhere in the back of the engine with the million other tubes & wires?

Which is the fuel pump bypass to keep the pump going?

Thanks

 

[Don W.]

Re: Fuel Delivery Issue

Thanks for that. The Regulator is new and the fuel pump is new (although I put it in and could have screwed it up).

Pressure drops from 38 to 8 as soon as pump stops.

Another dumb question, where are the injectors? How easy/hard are they to get to?

For the life of me I can't locate a "hose" in the fuel line. Is it tucked somewhere in the back of the engine with the million other tubes & wires?

Which is the fuel pump bypass to keep the pump going?

Thanks

OK, first what did the fuel pressure do before you changed the pump?

The injectors on in the intake manifold, at each port, in this pic they would be in the open holes next to the plugs.

The return hose comes off the bottom of the regulator. Also both hoses are accessible, sort-of, where they transition from the frame to the trans under the truck. The pressure line will be the one that comes from the fuel filter.

Are you positive you don't have a leak? Like maybe at the fuel pump?

The fuel pump bypass is a connector you'll find just hanging loose off the firewall near the dist.

 

[Syclone22]

Re: Fuel Delivery Issue

If i am correct your fuel pressure drops to 8 psi
if the pump priming stops you can install a
one way shut valve to keep the line pressure
to 40 psi or can jumper the fuel pump to keep
running if ignition is in the on position this will
keep your fuel rail pressure at 40 psi period !!! :tup:

 

[dgoodhue]

Re: Fuel Delivery Issue

I have had leaky injector before. The fuel pressure drops over a minute or two. An Instantaneous drop makes me think it's not an injector. Perhaps its the fuel pump check valve in the tank?

 

[tphilpot]

Re: Fuel Delivery Issue

Thanks Guys. I think it is a leak somewhere, most likely in the tank as there is no smell of gas anywhere. The injectors had been done about 2k miles ago.

It also slugs under load. That is the issue that lead me to fuel.

Basically I have spent $4k trying to fix the poor running issue and the last place is fuel. I will do the test described above and go from there.

Will report back upon completion of test.

This is very frustrating, borderline on parting our the car and moving on.

 

[Static]

Re: Fuel Delivery Issue

When the fuel pump was replaced was the rubber line replaced as well? Ive split that rubber hose before just after a fresh install of a fuel pump because I didnt use the right fuel line.:2cents:

 

[tphilpot]

Re: Fuel Delivery Issue

Thanks. I will check that. As a matter of fact, I am going to replace all the hoses as well.

 

[Danish-Syclone#0748]

Re: Fuel Delivery Issue

I have had a injector who were stuck after a short period of standstill.
It was at the paint shop, and when I had to pick it up I couldnt crank the engine. It sounded like the starter worked hard but could turn it. After some time I realized that one or more injectors were stuck open. I got the engine started and after that a LOT of black smoke were coming from the exahust. After a little while it stopped smoking and I had the idea to check the oil level. It was much higher then normal!? What I mean to say is¨:
I have had 2 experiences with stuck injectors
That one at the paintshop 2 years ago for no reason.
And yesterday after installing some std injectors I had cleaned a year ago. But somehow they dried out and 3 ouf 6 were stuck.

I removed the intercooler, throttle body and gained access to the fuel inector rail, removed that with
all 6 injectors still sitting on and did a engine turn. I saw one injectors just spraying 100% all the time(meaning stuck all the time) and two others stuck closed.
I
ts not that hard to dismantle, just mark and take pictures of everything

With your situation, why would there be 8 psi when a injector is stuck open? That would make it go to zero. I believe as the others say, a pump or fuel pressure regulator.

 

[tphilpot]

Re: Fuel Delivery Issue

Update--Pulled the plugs to see if there was a leaky injector. All 6 are black and covered in fuel. Any ideas why all 6 injectors would be open??

I have changed out the ECM and that didn't do it.

Is there a ground wire or something that might be failing that could cause this?

HELP!!!

 

[berzerker]

Re: Fuel Delivery Issue

heres my advise to you . call race proven motors in chatsworth ,CA and have the truck towed in . they'll get the thing diagnosed and fixed properly for ya .

 

[tphilpot]

Re: Fuel Delivery Issue

Without being rude to anyone. When I bought the truck a year ago, took it to RPM. $2.5k later, truck still ran poorly. They couldn't figure it out then. I have since replaced pretty much everything and narrowed it down to fuel.

 

[bshaw1979]

Re: Fuel Delivery Issue

Not trying to thread jack but...I'm having she same issue with pressure bleeding off. The truck runs great but when I key it on without starting it pressure goes to 42ish psi and drops quickly. Just upgraded the pump so I'm pretty certain it's not the pump. I'm thinking it's my regulator. I know you said you had an aftermarket one but might wanna double check it. I've been researching this and that seems to be the culprit a lot of the times.

 

[Don W.]

Re: Fuel Delivery Issue

Update--Pulled the plugs to see if there was a leaky injector. All 6 are black and covered in fuel. Any ideas why all 6 injectors would be open??

I have changed out the ECM and that didn't do it.

Is there a ground wire or something that might be failing that could cause this?

HELP!!!

Disconnect the inj harness connector and see what happens.

 

[tphilpot]

Re: Fuel Delivery Issue

Exactly when mine did the same thing, post fuel pump replacement. I bought and installed a new regulator, still have the same issue. Getting warmer.

 

[tphilpot]

Re: Fuel Delivery Issue

JUST A THOUGHT!!!!!!!!!!!!!
INTERESTED ?????????


Very interested. Sorry to be dumb, but what is this a photo of? Looks like the top of the fuel pump? I am a rookie, so alot of this stuff is new to me.