Ok, so I feel like this should be easy and I'm being stupid, but I have no idea how to check the fuel pressure on my car. I have the 2.8 MPFI engine.

I have the tools to test, but I don't know what I'm looking for. I know I need to plug in somewhere to test the pressure, but I have no idea where or what I'm looking for as well as what pressure it should be at.

If anyone has any info or pics to point me in the right direction that would be great. I have a fuel pump and all ready plan to replace it because it was being funny 5 years ago before the car was parked. Now, I'm trying to see if there is pressure or not because it won't start. I have to replace the ignition coil (I all ready did the pickup, and ICM). I get spark sometimes when cranking, but not consistently. So basically I want to be able to check fuel pressure if the ignition coil doesn't solve it.

Thanks in advance for any guidance.

 

I am waiting for my fuel pressure kit which I have ordered from ebay. Below is the link on what it looks like.
http://www.ebay.com/itm/230835797011...84.m1497.l2648

For instructions: http://actron.com/product_detail.php?pid=16174

There is a schrader valve on the fuel rail which is located between the upper and bottom plenum. Marked in red.

Just curious, do you have to release the fuel tank in order to replace the fuel pump ?

 

Do I have to pull the top of the manifold to get at that as it appears? If so I can test fuel pressure by just turning the key in the on position but not trying to start correct?

If so do you know what the pressure should be?

And no I'm dropping the rear to do the fuel pump. The only good thing is I have to drop the rear anyway because I need new axles so I figured whether the fuel pump is shot or not I'm just going to do it all in one job to make it easy. My one car has the cutout, but this car I don't want to do that. And no I didn't do the cut out in my other car. I found it when stripping it down for a restoration (that's another side project that got put on hold to get this running as my daily driver)

Thanks for the pic too because I've been trying to locate that and couldn't figure out why I couldn't find it. All makes sense now. Thanks for the help

 

No you don't have to pull the top manifold. I don't know about the pressure on 2.8L, ask in the forum or use the search.

I need to know the fuel pressure about my 3.1L

I might need to change my fuel pump and found about the cutout and thought to share instead of dropping the tank but you gonna do it anyway. Good luck !

 

Fuel pressure has been discussed at least a dozen times in the last 2 weeks or so...

37-47 PSI key on, engine off, 4-10 PSI less running. Fuel pressure should hold for 20 minutes after key and pump off without losing so much as 1 PSI pressure.

No, you don't need to pull the upper plenum to get the fuel pressure test connection made, but the placement of the vacuum T in the back of the plenum makes the connection pretty difficult compared to some cars.

 

Thanks for the updates. I did finally see it. Still have to get the valve to break loose and test, but first was trying to make sure the timing was on right. Problem is the battery died so gotta take that to autozone for a charge. Hopefully I'll know more by this weekend

 

I have 1991 3.1L Camaro, does it have a schrader valve to check fuel pressure? If not how do you check it?

 

Same as the post by Mav. The one above.

You need a fuel pressure guage to test, if you dont have one go rent one or buy one from your local parts store, toss it on the car and see what happends.

 

I guess I should be a little more specific in my question, if it does have a schrader valve, WHERE is it located on a 1991 3.1L Camaro? I know you need a guage, I have one of those, but if no valve exists, HOW and WHERE do you check the fuel pressure on this engine?

thanks

 

The shrader valve is located on the rear of the fuel rail, closest to the fire wall. You know where all your vac lines coming off the upper intake are? Look under there and your find it, it should still have a cap on it.

 

Yeah thanks we found mine, was 42 psi so pump is fine. Thanks for the help!

 

was it ok when the car was running? The psi?

 

We didn't check it with it running, my dad said it doesn't make a difference. The car actually runs great. I bought it in May and since then two times I have driven it about 60 miles one way and for some reason the first time I had a problem (I live in Central Florida) I was on the turnpike and it was running great then it just lost power and shut off. I coasted to the side of the run and I tried to restart it and it started but ran really rough and shut off again. I let it sit a few seconds and again the same. I let it sit for about two or three minutes, started right up beautifully. I went about 2 miles and again the same thing. This time I let it sit for about 15-20 minutes and it started and went about maybe 6 miles before it happened again. I just keep this up with it sitting for few minutes and again it would let me go a few miles and stop. I finally was able to stop at a Publix and let it sit for about a hour while I waited for help. I then discovered that my fan wasn't working (it's wired from a seperate ground and I control it via a toggle switch) I don't like running it over 190'. When my help arrived they followed me and it ran about 12 miles before just cutting out again. It was running around 220/230 then I figured it was cutting out to avoid over heating. We let it sit about 3 or 4 hours and got it after dark and it ran good the remaining 7 or 8 miles to my destination but the temp was getting high when I hit a few stop lights but other than that ran good. My dad discovered my fan switch had gone bad and replaced it. I drove home (again about nearly 70 miles) and didn't have any trouble and ran great. I drove it daily after that around my town for weeks and I didn't have a problem. A few weeks ago I drove it again back about 60 miles and this time I was sitting at a stop light and it cut off again. Same again, started but ran rough and then let sit for about a minute and started but same ran rough or it would run but shut off after a few seconds. When it would run, I limped through a stop light and it died on the other side (thank god!) Let it sit for about 2 minutes fired right up and let me go about 1.5 miles before dieing again. This time I let it sit for about 15 minutes and car ran great the remaining 2 miles I had to go. Came back home a few days later 60+ miles no problem, runs like a star. I drove to Orlando last Friday and no problems coming or going. It runs great 98% of the time and is a pleasure to drive on the highway. The ONLY thing it does have a problem with is (might be the sending unit) is the gas gauge will go up when I press on the gas and will go down when let off the gas or come to a stop. I can't let it get to far down past half or it will die when turning. Also, when you first start it up and get to your first stop when your almost to a complete stop it will act like it wants to die but revs right back up again. It may do it every time you stop, if your not going far or once it gets warm it acts fine and won't do it every time. The man I bought it from told me it needed a y pipe and that he put in the fuel pump backwards (not possible cause it wouldn't work and I can hear the pump come on every time I start it and the 42 psi check today) and about the gas gauge. I also use Lukas oil treatment in it regularly and like I said other then the two fore mentioned issues, it runs like a star all the time every time! Sorry this is long but wanted to be through. So if you have any ideas as to why it does these things let me know. I have read on here about how people have had a similar issue with it stopping and then after letting it sit it runs fine. I read that it gets hot in the fuel tank and it shuts off. The previous owner took really good care of the car and replaced the injectors, sensors, etc. It also only had 127xxx miles on it when I bought it in May and I just turned 129xxx now. It doesn't leak anything and I just recently replaced the power steering return unit (not pump) but where the sending unit is cause the hose had a slight leak and it was leaking under the car $21.00 fix and runs great. My dad fixes my cars so I know it's done right and for years has done all the work on my family's cars. So if anyone has any ideas let me know.
Thanks

 

Cool, well if she runs great thats awsome man. Have fun.

 

I am actually a women lol but thanks anyways. Any ideas as to why it will try to shut off but then rev back up immediately after coming to nearly a complete stop? That's the must annoying thing about the car.

 

Sounds like you have a variation of problems. With the fuel guage going up and down when you press on the gas sounds like a ground problem.

If he put a fuel pump in, I would start there. You are saying if it gets down to 1/2 tank it will die when turning.. Can you smell gas at all from the back of the car. I am beginning to think that he either didn't install the pump right or didn't put a new O-Ring on when he installed the locking ring on the tank. Next I would inspect the entire fuel line , change the filter, and ensure all fuel lines are properly installed all the way to the engine and not leaking. It really sounds like a fuel issue.. So testing the fuel pressure with the engine running does matter. Every time I have had a fuel pump fail is after it runs a little while and gets warm. Keep the Pressure gauage with you, if you are driving it and it dies, hook up the guage and see what your pressure is at then. Determine how long it takes the fuel pump to prime on a average.. Usually the ECM will allow it to pump around 5 seconds. If it doesn't prime or pumps too long, it might also be a clue. Keep us posted on this problem. I give you credit as you are really determined to drive this.. If mine ever breaks down more than 1 time, I call AAA and have it towed to my garage..

 

Well, there are several issues going on at the same time, and yes, you DO need to get the fuel pressure reading when running.

1. 90-92 cars have a 1227730 ECM. This ECM has programming called "anti-stall". It will allow the engine speed to get to a certain point before it opens the idle air controller up to attempt to bring the engine speed back up, which is the high-rev thing.
2. Test the fuel injector resistance, on each injector, when cold AND when it's failing. Any injector below 11.8 ohms goes in the trash (as per GM).
3. A common problem (and GM service bulletin) on the 90-92 cars is a hot stall... They have a common problem with the ignition wiring, something about the wires rubbing their insulation off and shorting out or something along those lines. I thought I had a link to the info bookmarked, but I don't (or I deleted it).

I had installed a complete engine harness from a 91 into my 87. Keeping in mind that I could go 400 miles non-stop with no issues whatsoever with the old harness... I'd get the harness in and everything would be peachy for about 3 weeks. And then it would start randomly stalling (same issue you have). I first thought the ignition module (in the distributor) had crapped out, so I replaced that. And then it did it again. So I replaced the ECM with another from the JY. Same thing. Pulled the harness out and reinstalled the factory 87 harness, and no issue. So now I've been using that harness (from the 91) for spare wires, except the ignition stuff that I threw out. When the harness was acting up, I noticed that the engine would stop turning before the injectors would quit firing in sequence, almost as though there was nothing to light the fuel being squirted into the intake. Again, keep in mind that the engine and all parts EXCEPT the harness were unchanged and worked just fine with the older wiring. There have a been a couple lucky people on here with the same issue who got brand new wiring harnesses from GM due to this issue (but don't count yourself as lucky).

Buy a spare spark plug. When the car is acting up, pull the spark plug wire off of the center of the distributor cap (the other end is attached to the ignition coil) and put the spark plug on it. Hold it against a good ground (intake plenum bolt) by the wire boot, and either crank the engine over or have someone do it for you if there is someone else around. No spark means a problem.

 

This is one of the best fuel-pressure drivability threads I've read on this forum.

One thing I will add:
When testing fuel pressure, you will benefit if you use a good quality tool, and which has a long-enough hose between the fuel-rail fitting and the readout gauge to allow you to position the hose between the engine bay and the windshield. This will allow you to secure the readout gauge in a location where you can observe the gauge during a road test. This is especially helpful where fuel-delivery issues are suspected during cornering.

Yes, I know I'm necro-posting.

Good thread!