Need some input (temporary fix)

JMH1950 · Post by **JMH1950** » Fri Apr 26, 2013 5:04 pm

For quite awhile now the car ('94 SSEi) has been crapping out at around 3000 rpm. Just hits a wall or surges depending on the day. This hasn't bothered me too much cause I mostly drive it back and forth to work however I am now trying to sell it.

A few days ago I took it for a longer drive, after about an hour it started crapping out a lower and lower RPMs, then it would quit altogether. It would start up again immediately and keep going for about 10 minutes then quit again. Since then on shorter drives, it just craps out at 3000. As long as I don't boot it, all is well.

So far I have done the following:

Pressure test fuel rail - right on spec according to all the info I've got
Replaced fuel filter
Replaced fuel pump relay
Replaced ICM and coils with known good ones
Replaced the PCM with known good one and a second known good one (because I could)
Checked and cleaned all the grounds I could find

Plugs and wires were also changed earlier on after problem first started

So, even though fuel pressure is right on, could it still be the fuel pump? Seems to me that I've covered everything else.

I have someone who is very interested in buying it, he knows it has a problem, however I can not in good conscience sell it like it is without knowing for sure what is wrong with it.

RJolly87 · Post by **RJolly87** » Fri Apr 26, 2013 5:42 pm

My thought is to try driving or loading up the engine with the fuel pressure gauge connected.

Other thoughts include MAF issue (unplug it, see if it is better or worse) or plugged cat (disconnect exhaust).

JMH1950 · Post by **JMH1950** » Fri Apr 26, 2013 8:15 pm

I haven't tried driving without the MAF connected, but did disconnect it while idling and it ran like *shoot*.
I can say for sure that the cat is no factor in this issue

I would have to get a longer hose on my pressure gauge before I could drive with it attached and actually see it.

Didn't mention before but with the car in neutral it will rev right to the limiter without hesitation.

RJolly87 · Post by **RJolly87** » Fri Apr 26, 2013 8:46 pm

It can idle crappy with the MAF unplugged, the biggest test is how it drives. If it has the same characteristics on the drive, or if it takes on a whole different attitude. I have confirmed 2 MAF related issues this way, one of which the car idled like absolute crap when it was unplugged, but when accelerating, the engine went from hitting the wall at a higher RPM, to pulling all the way up the RPM band as it should.

Of course, I wouldn't get in to the boost too much, but you should know pretty quickly.

One MAF was replaced (we didn't think of cleaning it, '94 SHO), the second was cleaned, and it fixed right up ('97 Crown Vic).

JMH1950 · Post by **JMH1950** » Fri Apr 26, 2013 10:21 pm

One MAF was replaced (we didn't think of cleaning it, '94 SHO), the second was cleaned, and it fixed right up ('97 Crown Vic).

I did spray the crap out of it after the problem first showed up, with no improvement. I will try unplugging it and taking it out for a drive. We'll see what happens.

I appreciate the input.

mylittleblackbird · Post by **mylittleblackbird** » Fri Apr 26, 2013 11:34 pm

spraying it is not always sufficient. A q-tip and some isopropyl alchy or other qualified electronic cleaner will be sufficient. Just be very gentle when working on the MAF elements. They can be unnaturally delicate.

Or, ya know... unplug it and see if that helps for a run or two.

Post by **Bugsi** » Sat Apr 27, 2013 1:18 am

I was going to suggest looking at the MAF too. When mine failed it didn't throw a Check Engine Light, which I found odd for something that could completely prevent the car from starting. So yes, definitely check the MAF.

JMH1950 · Post by **JMH1950** » Sat Apr 27, 2013 1:22 pm

OK, I drove it with the MAF disconnected, no difference in symptoms.

I did notice today that there was no residual pressure in the fuel rail and the car takes a little longer cranking to start lately. I was going to take the pressure regulator off but it seems to be part of the fuel rail, is that correct?

mylittleblackbird · Post by **mylittleblackbird** » Sat Apr 27, 2013 2:45 pm

I can't speak for the 95 an earlier ssei, but I would assume it is. So, if you prime the fuel system, it bleeds off immediately after key off?

Also, could you give us a summary of your fuel pressure testing procedure? Perhaps your fuel pump is not able to keep up with the fuel demands?

If you have the means to do so, hook that fuel pressure gauge up , start the car, hold the brakes, and increase the revs. If your fuel pressure starts to drop off, at the higher rpm, that could be why you're stuck at 3k. It may be able to build the pressure, but if it can't supply the volume then it's needing replaced.

JMH1950 · Post by **JMH1950** » Sat Apr 27, 2013 3:13 pm

it bleeds off immediately after key off?

No, it will hold some pressure for awhile, not sure how long.

Also, could you give us a summary of your fuel pressure testing procedure? Perhaps your fuel pump is not able to keep up with the fuel demands?

1 - hook up the gauge.
2 - turn on key and observe pressure. Shoots up to 40 psi then stabilizes at 35 then goes back to 10 after the pump stops priming.
3 - start engine and observe pressure. Steady at 35 untill I increase rpm, then goes up to 40 for a second before stabilizing at 35.
4 - Put car in gear, hold brakes and increase rpm. Pressure rises to almost 40 and stays there.

mylittleblackbird · Post by **mylittleblackbird** » Sat Apr 27, 2013 5:59 pm

A general rule of thumb is that your pressure should not bleed off 2psi or more every 3 to 5 seconds. You should be able to hold close to operating pressure for 10 minutes or more with the engine off. So when you say it drops to 10 after the pump shuts off, is that drop happening quickly or not?

JMH1950 · Post by **JMH1950** » Sat Apr 27, 2013 7:19 pm

So when you say it drops to 10 after the pump shuts off, is that drop happening quickly or not?

Within a few seconds.

mylittleblackbird · Post by **mylittleblackbird** » Sat Apr 27, 2013 7:55 pm

Then you have an issue with either your pump check ball, or possibly a clogged/stuck injector. Supposedly you can stick a 194 bulb into the injector plug to verify that it is receiving a signal to open. If the light stays on constantly, you have a bad injector driver. Since you've already replaced the PCM, that would seem unlikely. I would venture that you need either a new pump, or to get your injectors cleaned out. I understand that an overnight bath in B12 chemtool can be somewhat effective at this, but it isn't 100% certain to work. I used it for a set of LT1 vette injectors, but the owner still ended up buying a new set unfortunately.

To find out if you have an injector that's stuck, use either a mechanics stethoscope or a long screwdriver(put the handle to your ear, not the pointy side), and listen to each injector for ticking. If they are all ticking, most likely, your fuel pump has an issue with maintaining pressure.

The pressure should not bleed off within a few seconds.

JMH1950 · Post by **JMH1950** » Sat Apr 27, 2013 9:56 pm

The pressure should not bleed off within a few seconds.

I totally agree, however this is just a recent thing. 3 days ago when I put the pressure gauge on I had to bleed some pressure off first (first thing in the morning before starting the car). This may be a related problem, and not helping any, but certainly not the original cause.

OK, I admit that I'm looking for an easy answer that may not be there. I just don't have the funds to have the pump replaced and don't have the facilities to do it myself. However it is looking more and more like the pump is the culprit.

mylittleblackbird · Post by **mylittleblackbird** » Sat Apr 27, 2013 11:52 pm

I understand. It's easy to say what needs to be done, but completely different to go and do it. I hate to think that it's the fuel pump. However, I can't see a lot of other solutions. Are your BCS/BCA working? Are you dumping boost at 3k rpm?

JMH1950 · Post by **JMH1950** » Mon Apr 29, 2013 4:14 pm

Are your BCS/BCA working? Are you dumping boost at 3k rpm?

It hold boost the whole time it's acting up.

mylittleblackbird · Post by **mylittleblackbird** » Tue Apr 30, 2013 8:38 am

And the fuel pressure when it starts sputtering out is still within spec?

JMH1950 · Post by **JMH1950** » Tue Apr 30, 2013 4:35 pm

mylittleblackbird wrote:And the fuel pressure when it starts sputtering out is still within spec?

Don't know about that. The hose on the gauge is too short to view it when driving unless I want to take the hood off (which I don't).

As soon as I get a chance I am going to raise the rear of the car and beat the crap out of the bottom of the fuel tank. If things improve, then it's probably crap clogging the intake screen. Until very recently this has been a random thing, some times no problem for a week or two, then it acts up for a few days, then not.

mylittleblackbird · Post by **mylittleblackbird** » Wed May 01, 2013 8:26 am

Another thing that was mentioned in another thread, something I often forget about. Perhaps your cat is plugged.

RJolly87 · Post by **RJolly87** » Wed May 01, 2013 8:33 am

mylittleblackbird wrote:Another thing that was mentioned in another thread, something I often forget about. Perhaps your cat is plugged.

He did advise that the cat is not a factor.

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