'86 2.8 v6, rebuilt from a basketcase so I have no idea what kind of shape the parts are in. The car sat for about 8 years before I got it so I replaced both the pump and the filter before running it. I figured I might as well replace the filter again thinking that I may have cleaned any more debris out of the tank and had it go through the filter.

The car has been getting terrible fuel economy ever since I got it running agin and is very sluggish so I thought I'd replace the fuel filter and see if that does anything to help. I drove the car to a convenient spot in my parking lot, went inside to grab tools, came out, and depressed the valve on the fuel rail. Nothing. No fuel came out or anything. So I primed the pump a few times by turning the key to on and off and tried again. This time it just sorta dribbled out.

I went ahead and replaced the fuel filter and it was a bit clogged, but not too bad.

However, I'm thinking the culprit is that I've either got a leaky injector(s) or a bad fuel pressure regulator. Any suggestions as to what I should do next? The fuel pump is new as of 6 months ago so I suspect its still good.

I'm thinking that I ought to replace the fuel pressure regulator perhaps? The regulator is the cheaper option at this point

Holy crap, I just checked prices and a rebuild kit for the regulator is 60-80 at most retailers. RockAuto has a closeout item for $30 and I've been meaning to pick up some new front shocks from them anyway so I may go ahead and order it.

Should I take a stab at rebuilding the fuel pressure regulator or is there another more likely culprit? I gues if I take the fuel rail out I could go ahead and leave the injectors plugged in, turn the key over to prime the pump and if I get a leak from an injector that would tell me that I've got issues there too.

The fact that the pressure doesn't stay long isn't much of an indicator of anything

Check the timing. - check the thermostat

Does your check engine light come on when you turn the key to start? Is it on otherwise?

Yes, the SES light comes on when I turn over the key but goes off when I turn over the car. I have no codes stored. New thermostat, and I just put in a rebuilt dizzy and set the timing a couple tanks back. Still no go. I'm not sure how timing would affect fuel pressure? I should get a good squirt of pressurized fuel coming out of the rail when I depress the scrader valve but it just barely dribbles out.

Fudge. Maybe my pump is bad? Less than a year old though... I may try to borrow a fuel pressure gauge and see what happens when its running.

The rail should hold pressure at least for a while after turning the key over to prime system but its bleeding down really fast somewhere... either the check valve in the pump (which I doubt as its fairly new), super leaky injectors, bad fuel pressure regulator, or.... something else??

When my fuel pressure regulator failed a few weeks ago, the pressure in the rail would drop very quickly after the pump shut off. We're talking 50 PSI to zero in about 2 seconds (I have a fuel pressure gauge). The diaphragm in the regulator ruptured, and was allowing fuel to leak into the vacuum line (and up into the intake). It caused the fuel economy to drop dramatically, and caused the engine to run really rough on cold start-up.

If that happened to yours, it will be easy to spot. Just detach the vacuum line from the regulator and see if fuel comes out.

That sounds an awful lot like mine is. I have removed the cold start injector, but even then the car has a hard time starting and I have to let it run for a few seconds before I can put it into gear or the motor stalls.

If I can reach it, I'll pop the vacuum line off and see if I can smell fuel.

Looks like its going to be about $93 to ship a new regulator kit and two new front shocks (desperately needed) so I may just go ahead and order them if I can verify fuel in the vacuum lines.

[This message has been edited by Alibi (edited 03-09-2010).]

I bought a new fuel pressure regulator from Auto Zone today for $43 plus tax.

------------------
Jonathan
1987 Notchie - undergoing surgery
I'm not a mechanic but I play one in my garage - me
Power tends to corrupt, and absolute power corrupts absolutely. - Lord Acton
Those who hammer their guns into plows will plow for those who do not. - Thomas Jefferson

[This message has been edited by Boostdreamer (edited 03-09-2010).]

quote Originally posted by Boostdreamer: I bought a new fuel pressure regulator from Auto Zone today for $43 plus tax.

The whole assembly for a 2.8? The only things I've been able to find are just the rebuild kits with a new spring and diaphragm. Even on the Autozone site. I may have to go by a store and see as I've got $15 left on a gift card that needs to be used up...

My fuel rail does the same thing only worse. Mine won't start and run for more than a few seconds. I'm changing mine tomorrow.

Harbor Freight has a Fuel Injection Pressure Tester for $20 and a Timing Light for $15. Then I found the Tamper Resistant Torx bits in a small set at NAPA for $11. Nice little set for the cost of one bit from the Fiero Store.

Here's the test I did. Determine which of your two fuel lines are the supply ( goes through the filter ) and the return. The lines between the filter and the male connectors on your engine are rubber encased in corrugated plastic. Pull the plastic back in the middle of your return line and clamp it with vice-grips or similar. Now turn on the key to prime the fuel rail. Press the valve or attach your pressure tester. You should have a much bigger fountain of fuel or a reading of fuel pressure now. The pressure regulator can go bad and let all the fuel run back to the tank so you will never build up any pressure. If you block that return line, the fuel has nowhere to go and so will build pressure. Do not leave the hose clamped for any extended period of time and do not drive with it in place! Not a fix, just a quick cheap test. You don't want to damage the hose.

After you see that you have pressure, attach a fuel pressure tester guage to the schrader valve. Remove the two 5 amp fuel injector fuses in the fuse block under the driver's dash. Turn the key on again and see if the pressure drops. If it does, you have one or more leaky fuel injectors which may include the cold start injector.

Jonathan

You shouldn't need to replace the entire regulator assembly, unless the top cover is damaged. If in fact your diaphragm is ruptured, then replacing the diaphragm / spring assembly should fix it.

[This message has been edited by Blacktree (edited 03-09-2010).]

quote Originally posted by Boostdreamer: My fuel rail does the same thing only worse. Mine won't start and run for more than a few seconds. I'm changing mine tomorrow. Harbor Freight has a Fuel Injection Pressure Tester for $20 and a Timing Light for $15. Then I found the Tamper Resistant Torx bits in a small set at NAPA for $11. Nice little set for the cost of one bit from the Fiero Store. Here's the test I did. Determine which of your two fuel lines are the supply ( goes through the filter ) and the return. The lines between the filter and the male connectors on your engine are rubber encased in corrugated plastic. Pull the plastic back in the middle of your return line and clamp it with vice-grips or similar. Now turn on the key to prime the fuel rail. Press the valve or attach your pressure tester. You should have a much bigger fountain of fuel or a reading of fuel pressure now. The pressure regulator can go bad and let all the fuel run back to the tank so you will never build up any pressure. If you block that return line, the fuel has nowhere to go and so will build pressure. Do not leave the hose clamped for any extended period of time and do not drive with it in place! Not a fix, just a quick cheap test. You don't want to damage the hose. After you see that you have pressure, attach a fuel pressure tester guage to the schrader valve. Remove the two 5 amp fuel injector fuses in the fuse block under the driver's dash. Turn the key on again and see if the pressure drops. If it does, you have one or more leaky fuel injectors which may include the cold start injector. Jonathan

I'm going to try this tomorrow if the weather is nice. So if I block the return line, run the car in idle for a minute, kill the engine, then test the valve? If lots of fuel comes out, then that means that the regulator or injectors are leaking?

I wouldn't try to start the car like that. If it is running, the pump will continue to run and it could be damaged or something else might give out from excessive pressure. Just use the 2-second prime that happens when you turn your key on.

Jonathan

I primed the pump, turned off the key, and tried the valve. I got a dribble, but no squirt. So... maybe ten seconds between walking around the car and depressing the valve?

I'm really leaning towards a bad regulator then... at least I hope its the regulator because I really don't have the money to replace the injectors

quote Originally posted by Alibi: I primed the pump, turned off the key, and tried the valve. I got a dribble, but no squirt. So... maybe ten seconds between walking around the car and depressing the valve? I'm really leaning towards a bad regulator then... at least I hope its the regulator because I really don't have the money to replace the injectors

Do the same thing again but clamp the return fuel line first. You should see a big difference in how much fuel squirts out. If you do, that's a good thing, you've found your problem. MUCH cheaper to replace the regulator than the injectors!

Jonathan

Awesome, I'll try it tomorrow. I imagine I could find a set of injectors in the mall but if I only have to pay $30-40 for the rebuild kit (partially with a gift card left over from x-mas) then I'd much, much rather have that be the problem. I really hope this solves some problems I've been having with my GT...

If it turns out to be the injectors, let me know. I can hook you up with a good used set.

[This message has been edited by Blacktree (edited 03-10-2010).]

quote Originally posted by Blacktree: If it turns out to be the injectors, let me know. I can hook you up with a good set.

Awesome, I certainly will keep that in mind.

Definitely test the regulator or better yet, test the pump by pulling the supply line and attaching a pressure gauge before the regulator. If your fuel tank looked anything like mine did and you did not really clean out all the corrosion you will most likely find that your pump is ruined and the filter sock over the pump looks like it is completely clogged with very small rust bits. Don't ask how I know this...

Hopefully it is not the pump but keep an open mind if everything else checks out ok.

Charlie

Changing the regulator didn't help mine. I'm still only getting 10 psi of fuel. That much seems to hold.

Jonathan

quote Originally posted by Boostdreamer: Changing the regulator didn't help mine. I'm still only getting 10 psi of fuel. That much seems to hold. Jonathan

That sucks. Must be a bad/weak pump then

I'd give you mine if we were closer. It sure isn't doing me any good. The one I took out still looks new.

Jonathan

No worries, I went ahead and picked one up at AZ. I was hoping to be able to beat the rain but it already started so I'll just have to wait for it to die down or just do it later. I'd rather do it as soon as possible because if it fixes my MPG issues, then I'd be saving some good coin in transportation costs over spring break.

If this doesn't fix it, then it must either be leaking injectors or a bad valve in the pump or something.

The part at AZ was almost $70 (ow) but if it fixes my problem then I'll be saving that much tenfold in fuel. If I didn't need it for this next week I would have just ordered it off RockAuto but oh well.

You got gouged. Mine from AZ was $47 plus tax. Check their website then call them while you are sitting there looking at it. Maybe they will adjust your bill.

Jonathan

[This message has been edited by Boostdreamer (edited 03-10-2010).]

Dunno... the website shows it at $67 for me.

http://www.autozone.com/aut...=14999999&sortType=& store=1607&isSearchByPartNumber=false&fromWhere=&fromString=search&counter=0&itemId=165-0&navValue=14900165&filterByKeyWord=fuel+pressure+regulator&productId=79671&searchText=fuel+pressure+regulator&categoryDisplayName=Fuel+Delivery&parentId=49-0

See if that link works, if not then try the same part with my zip code of 66762

Must be a regional difference thing. I just looked at it and it was $46.99 here. Then I clicked on your link and it also came up $46.99 but it auto-linked to my local store.

Jonathan

[This message has been edited by Boostdreamer (edited 03-10-2010).]

Weird.

Anyway, I have another symptom. I depressed the valve again and I actually got a pretty good, long spray out of it this time. I drove the car maybe 5 miles to the AZ and back, and its been parked for at least an hour.

Before, I would prime the system and only get a dribble. I also drove the car across the parking lot (50 yards maybe) and parked it, checked it maybe half an hour later and got nothing when I pressed in the valve.

So is it normal for the regulator to sporadically work and then fail? Or should I be looking into something else now?

starting to sound more like the fuel pump... If your reg has a rupture it should be consistently passing gas! "whoops, sorry!!! )

Charlie

I certainly hope its not the pump.

I did some more research though...

I dug out my crappy harbor freight pressure gauge and hooked it up. It read zero pressure when just hooking it to the fuel rail.

-then it jumps up to about 40 when I prime the pump and quickly drops down to zero (within a few seconds)
-I turn the motor on and it stays at a very even 40-41 PSI when running
-as soon as I turn the motor off, the pressure drops down very quick to about 10-15 psi then slowly bleeds down to zero

So... does this still sound like a bad regulator? I cant seem to get at the regulator well enough to pull the vacuum line off to check for fuel in the vacuum line though. I think that its time to pull the upper intake off and then the fuel rail, prime the pump and see if any injectors are leaking. If the injectors are good, then I think it'll then be time to replace the regulator.

Make sense?

Its not too cold out tonight so I think I'm going to go ahead and do it along as I can find my 12 point 10mm socket to remove the plenum bolts...

If the diaphragm in the regulator is ruptured, the fuel will flow up the vacuum line into the intake. So if you can't reach the regulator, you can disconnect the vacuum line at the intake manifold.

quote Originally posted by Alibi: I'm not sure how timing would affect fuel pressure?

No it doesn't affect fuel pressure - It would however affect your MPGs

quote Originally posted by Blacktree: If the diaphragm in the regulator is ruptured, the fuel will flow up the vacuum line into the intake. So if you can't reach the regulator, you can disconnect the vacuum line at the intake manifold.

Another check, is to watch the fuel pressure as you open and close the throttle with the engine running. The fuel pressure regulator diaphram is supposed to change the fuel pressure with changes in the manifold vacuum.

I'm not a big fan of replacing parts without fully troubleshooting. It costs a fair amount of money and many times the replacing takes much longer than the troubleshooting would have.

As stated by others if you have fuel in that vacuum line you for sure have a bad fuel pressure regulator.

So according to this diagram:



I should pop the T off the passenger side of the motor after running it and check for fuel? Will it drip out or will it just be fumes? Or should I disconnect it while the car is running?

Pull it off and then just turn the key on and let the fuel pump prime. See what you have. Maybe try the prime more than once If no fuel on the prime, then start it and watch for fuel. You don't want to start it and having fuel running all over the top of your engine.

Makes sense?

Liquid fuel.

Ok, I've got a couple rags handy that I can stick under the lines after I pop them off. I'll go give it a try here in a couple minutes

Which trouble are you looking to solve? The poor mileage or how long you think the fuel pressure should stay there. It could very likely be bleeding back through the pump, which will in no way affect your mileage.

Do you have any hard starting issues? If so is it when the engine is cold? Warm? Does the hard start issues change depending on how long since it last ran (30 sec vs 5 min)?

A leaking injector that leaks enough by dumping gas into the engine I would surely think would also cause a rich condition light on your ECM.

So if instead you look at the mileage issue, lets talk about the sluggish preformance. Does the car idle well? When do you feel the sluggish performance is happening. Does the trouble seem to be not bad in the city but much worse on the highway?

You do believe you checked the ignition timing and you feel sure its correct right? You did the A-B short while you looked at the timing light right?

http://www.youtube.com/watch?v=3CzDk9wswG4

Any chance the cam timing is a tooth off? Who assembled the engine, and did that person feel certain about the cam timing when he/she put it together.

Any chance you have a plugged converter?

It would be good to run winaldl on this vehicle and see what the ECM says is happening.

http://winaldl.joby.se/

You need a laptop with a serial port, and a ALDL cable.

[This message has been edited by phonedawgz (edited 03-11-2010).]

If you decide to check the injectors, don't forget the cold start injector.