Fuel Pressure Test on a 1995 Fleetwood Brougham

[RubberCarrot]

Hi All,

Been a while since posting anything but I have a new quest.

I suspect my fuel pump is bad.  Not so much the pump side but the check valve side.  I understand the pump incorporates a check valve to prevent fuel from draining back into the tank.  I think that is my problem. 

When it sits overnight it will require some extra cranking to start.  If it sits three nights I have to fake the fuel pump out by cycling the key (on 10 seconds, off, repeat) 3 times.  If it sits a week forget it.  Get the starting fluid.

As soon as it fires you can turn it off and will restart fine, all day long. 

Displays no symptoms of a bad FPR.  I have been watching this progress for about a year and it is now to the point where I want to fix it to trust it.

I want to do a pressure test to validate my suspicions before dropping 200 bucks and a weekend of fun dropping the gas tank.  I read that there is a Schrader valve near the FPR at the back of the intake/block.  But I cannot find it!  That would sure make the pressure test part of this easier!

Do you guys know of this Schrader valve?  Where it is?  And if it doesn't exist, any suggestions on a likely place to tap into the fuel system to test it?

Thanks in advance!

RC

[rockfangd]

I am not sure if the 5.7l has a fuel pressure port. It would be right near the fuel inlet. I will have to see what type of injection you have to better answer exactly where it may be

[Logan]

No port......Lots of '80-90s GM TBI systems lack a port. You have to open a metal fuel line and install a inline gauge. Pain to do when engine is hot etc.....but so it goes....you need a kit to do it.

https://www.toolsunlimited.com/pdf/ToolsCat_74.pdf

 

 

 

 

 

[RubberCarrot]

Thanks guys.  I figured that would be my luck.

It is a tuned port injection.  Drivers side fuel rail has the FPR on the back of it (fuel feed comes into the FPR), then a crossover tube to the passenger side rail and the return line comes off the back that rail and heads back to the tank.

Seems like a perfect place to help us suckers out.  lol.  Then again, look where the original plug wires were routed. 

Welp, my fuel line tools are sitting on the front porch (just delivered today) and the O'Reilly's near me has a loaner pressure gauge begging for my deposit.

I am betting I will see great pressure when the pump is running (car runs and drives perfect) but will see the pressure drop off immediately when I turn it off.   It acts like it has to pump from the tank every time it sits overnight.

For the benefit of others, this is how it works:

1. Turn key on, fuel pump runs for 3 seconds and then stops, awaiting a signal from the PCM that the engine has fired.

2. Once engine fires the fuel pump turns back on.

3. No engine start = no more fuel pump action.  The engine can't start with dry injectors and a dry fuel line...

I did replace the coolant sensor (hoping for an easy fix) because if that fails the PCM may not be notified of a cold engine, preventing that extra shot of fuel on a cold start.  (Like the old choke) Obviously that was a fail.

You can work around the problem by cycling the key on and off a few times, leaving it in the on position for 5 to 10 seconds.  If it has only been overnight it will start.  More than 1 night = more games cycling the key.  Too much work on the battery and starter for my liking.

Also, there is supposed to be a red or gray wire plugged into nothing near the fuse/relay box near the firewall under the hood on the passenger side of the car.  Supposedly, this is a jumper for the fuel pump and if you hot wire it to 12 volts, it circumvents the whole mess and the fuel pump runs.  I have not looked for this wire yet.  Maybe later today.  I have a couple trees I have to whack down...

If I try that wire, I will report back for general knowledge.  Same goes for the pressure test, whenever I get to that. Or maybe I will just drop it off at a shop I don't like just let them do the pump. I'll make sure the tank is full! lol.

 

<sigh>

[Logan]

8 hours ago, RubberCarrot said:

It is a tuned port injection

LT1 engine? Different setup. It has a schrader valve. See attached picture....center right... It should be under a little black screw on cap

[rockfangd]

Thank you Logan for posting a pic. I thought TPI did have a port. I know TBI did not.

[RubberCarrot]

Thanks a lot Logan - I just went out and looked and sure enough, there it was, hiding under that fat wire harness!  You know what they say... Draw the guy a picture...

Here's a meaningless question: What is the triangular cover for on top of the engine/intake? Does it provide a "stash" of air for when you step on it or is it just baggage, though I will admit the manifold is not as pretty as some iterations. BTW, a 3 inch threaded PVC plug comes in handy for running the car with that cover off.  Better that stuffing a rag in that hole.  🙂

Much appreciated!  I am going to shoot to put that schrader valve to use this weekend.

Also, I did get to look for that wire to jump the fuel pump yesterday.  Sure enough, there it was.  Red wire.  Connected it to battery and let the pump run only as long as it took to walk around the car to reach in the driver's window.  Car started almost like normal.  I think that is to be expected as the fuel line and injectors had lost the pressurization they would normally start out with.  Gonna let it sit all week and see if it behaves the same way when I pull it into the garage for the pressure test.

[RubberCarrot]

Ok Guys - Update:

I'll keep this short.  Tell me what you think.

Car has sat for 6 days. Lately that would be mandatory starting fluid event.

I went out and connected the test jumper to bypass all the normal checks and balances to simply run the fuel pump.  I gave it a minute, tops, turned the key and it fired instantly.  What I expected.

Disconnected jumper and pulled it in the in the garage.

Put a pressure gauge on the Schrader valve (located after the FPR and both fuel rails.  Connected the jumper to run the pump.  It read 18 pounds.  (should be 43.5 - 47)

Started the car and it remained the same.

Raced the engine with no change.

Really raced the engine hard enough and long enough to cause a vacuum drop which should cause the FPR to increase fuel flow/pressure (if I have my facts straight).

When RPMs were increasing there was no change in pressure.  When I let off the gas, pressure bumped up to 20 for a split second, then returned to 18.

Not what I was expecting but close.  Because the pressure gauge retains pressure until the pressure release is pressed, I can't tell how fast pressure drops when the car is turned off, but I think that is a moot point.

I am going to replace the FPR first and pressure test it again after, because I really don't relish the thought of dropping the gas tank.

What do you think?  Think I will get lucky and the FPR is the culprit?  Or do you lean toward the fuel pump being shot and just maxxed out at 18 psi?  

Thanks guys.

 

[rockfangd]

It almost sounds like a plugged filter or weak pump, plugged strainer.

When the load is let off and pressure increases that would be normal. (uses more under load, less not under load)

I do not figure a FPR would cause a consistent low pressure

[RubberCarrot]

I agree with you on the weak pump/clogged strainer.  As a matter of fact, I am pretty sure that is what it is.

I am going to do the FPR first because if that spring is broken in there, maybe it is causing low pressure?  I really had to stop myself from ordering both FPR and fuel pump at the same time because maybe the gods will be in my favor and the FPR fixes the problem.  No point in dropping 200 bucks on something that I won't use unless I have to.

Fuel filter was replaced 1.5 to 2 years ago when I had to fix a leaking fuel line.  Only 2k miles since then, at the very most so I will let that ride for the moment.  I hate those fuel lines.  lol.

So, I will do the FPR, test pressure and if no fix, order the fuel pump and probably the filter too, just because.

BTW.  I paid the dues and got an ACDelco Gold FPR and when ordering the pump am going to get the Delphi (ACDelco not available) one, complete with hanger and sending unit. See, I remain hopeful but am a realist.  lol.  If I have to drop the tank, it will give me a chance to clean it out.

Not buying the cheap stuff either.  Heard too many horror stories and besides, the good parts are why these cars last and don't leave you sitting on the side of the road. 1/2 the fuel pressure it should have, but I'm not afraid to drive it to burn off the fuel in the tank!  🙂

I will report back when I get the FPR in.  Hopefully this weekend if it isn't too crazy hot. The more time goes by the more the heat kills me.  I'm in NC.  We get Winter, then 2 days of spring, then summer followed by 2 days of fall and then back to winter.  lol

[RubberCarrot]

OK.  You guys have had a nice break from my rambling.  But it's over!

I got knocked off my feet for a couple months!  Had a flashback to a herniated disk from 1991.  Getting old, disks are getting crushed, rewarding me with the most exquisite pain one could have.  So, took a while to make headway.

I was going to start by replacing the FPR but between Torx bolt nightmares and yours, mine and a buddy,s (20 years as a Ford Mechanic) instincts, I decided to go straight to the fuel pump.  

Man, that was a ton of fun. Can't wait to do it again.

Got the tank back in tonight, threw 5 gallons of gas in the tank, stuck a pressure gauge on the elusive Schrader valve and connected that secret jumper to make the pump run.  BOOM.  43 lbs.

Disconnected the jumper and turned the key and it fired up like it just ran 5 minutes before.  Interestingly enough, pressure dropped to 38-40 lbs with it running.

Took it for a test drive and it had its high RPM kick in the pants back.  So, on the road again.  I think the neighbors thought that it was gonna be on jackstands forever (I did it outside because if I squeezed it in the garage I wouldn't be able to open the beer fridge!. That just is not acceptable).  So they got to see it standing on the front bumper for two weeks.  lol.

Side notes for anyone looking at this job...

I only run non-ethanol gas figuring over time I would save $$$ on a lack of injector issues. Jury is still out on that.

I was curious to see what I would find in the tank in the way of debris and sludge.  Well, no sludge and very little debris.  It wouldn't have covered the bottom of a shot glass.

One piece of advice for anybody else looking at this job.  Save your money when it comes to buying tank cleaner.  I had every intention of making the inside of the tank sparkle but not possible with all the baffling they put in there.  (How the heck do they even do that with a plastic tank?)

Oh yeah!  Why in the world didn't they make that hole in the tank a half an inch bigger?  It's a hole. Less would definitely be more. The car would have weighed an ounce or two less and gotten so much better gas mileage.  Getting the old pump out was hard but getting the new one in there was a puzzle.  I had to reverse the intake sock because one end of it had a rigid piece inside that made getting it through that hole impossible.  Reversing it made it doable although it took more force than I would have liked.  Just a half an inch folks and it would be a no brainer.

Anyway, thanks again for all your input.  It was a definite help.

RC

 

[RubberCarrot]

Oh yeah... I bought a filter too, but based on the one in the car (being 1500 to 2000 miles old) and the lack of debris in the tank, I am just putting the new one on the shelf for future entertainment.

I know you were wondering.

Thanks again guys.  This forum is indispensable. 

 

[rockfangd]

Excellent to hear. The senders are a pain to get in and out, mainly if it is a plastic tank.