aggravation

Well my quest to find the problem with my car has reached desperate measures time. I'll be changing out parts until I find the culprit.

So, I'll remove the fuel pump and filter and install new ones. Since I have no faith that it could be so easy I expect to have a spare fuel pump when I'm done. Is there any particular way I should prep the pump for long term storage to keep it as a spare? Wash it out with a light oil or something...?

Also, to remove it can I just pull the hose that feeds the pump and pinch it off with some needle nose vise grips? Or should I plan on draining the tank?

I have a single pump 1988 model...

Sailmed

No need to drain the tank.
Just take a 3/8 extension and shove it in the hose...
Quick like

Mrmerlin

you could mix some fuel and marvel mystery oil and run it through the pump, tie rags areound your wrists before you undo any fuel lines and have a fire extinguisher handy. The rags will let you keep on working if there is a spill so the fuel wont run down your arms

David L. Lutz

Been gone for a week w/o a computer.
Any conclusions on your pump/problems?

aggravation

I have the car up on jack stands right now, new pump to be delivered tomorrow so I haven't been able to test it after a few tweaks I've made.
I found a hose from the gas tank fill neck to the vapor recovery system disconnected but I don't think that could introduce false air unless other parts like the vacuum operated valve and/or the check valve was allowing air to be sucked into the intake from that disconnected hose....

I also am replacing all the #53 relays since I found the fuel pump relay went bad when I was switching it with the horn relay...I was careful but it quit working just from the unplug and plug back in process....

So my logic is, if something is intermittently stopping the fuel from flowing it has to be either mechanical or electrical...I'll give it new relays and filter and pump to eliminate those items.
I reattached the loose hose.

Now once those parts are in I'll fire it back up for a ride and see what's up.
My guess is it will still be high idle and surging.
At that point it will be new MAF time because it's cheaper than a new LH....

I hate being a parts changer but I'm running out of ways to diagnose it!

I'd like to be able to unplug and replug my ISV connector just to make sure it's in snug and plugged in correctly but I haven't found a tool that will let me reach it without lifting the manifold. If anyone has done it in place let me know how!
For those who want to play along at home, my symptoms are a steady but high idle at 1200 rpm's and surging at cruise/light throttle usually around 3000 rpm's associated with the AF gauge spiking up to 19 or 20 and the car is lurching not gently surging...

Charley B

Those sure don't sound like fuel pump or filter induced problems.

aggravation

I know.
I'm guessing I'll find I have either a bad MAF or bad LH.

The theory behind the pump and filter is, if the fuel pump were seizing up intermittently or the filter partially clogged couldn't it create brief periods of lean conditions? The LH would open the injectors enough for cruise conditions but the fuel pressure drops out for a split second, or the filter starves it just enough, then the O2 sensor adjusts... letting the mix vary from stoich to lean.
While under heavy throttle the injectors are open more so the swing goes from slightly rich back to stoich.

It's a long shot but since I already have a new filter on hand and the relays are needed anyway I figure changing out a 20 year old fuel pump isn't too bad of an idea to be able to eliminate the possibility plus the preventive maintenance aspect...

I'm wide open to suggestions since this has been going on for months with no solution in sight.
Some days I just want to put the car back to stock and sell it and the supercharger kit seperately and buy an M5....but then I look at that Shark from a certain angle or take out and floor it through second and third gear and the smile factor makes me forget all about the M5....but DAMN IT I wish I could just go for a drive at the speed limit and enjoy it!

Mrmerlin

can you try your LH and MAF in a good running car? Does the LH have chips in it? How old is the MAF?

aggravation

*I don't have access to another car to swap parts into.

*My LH has SharkTuner PEM's in it. They are re-writable chips that the SharkTuner can reprogram while they are in the car. the maps that are programmed into those chips right now are the latest files that Tim Murphy created for the StageIII kit.
I've tried a few different custom maps from Tim and there doesn't seem to be any difference.
At one time I thought maybe the PEM's could be a little loose in the socket creating the problem but the consensus was that wasn't likely. I did take the PEM's out at one time and put in the actual chips that Tim sends with his kit (most people wouldn't have the Shark Tuner and PEM's so he burns chips tuned for the StageIII ) so basically at that time it would be the same data on the chips just a different piece of hardware in the socket. Doing that didn't change anything.

*The MAF is original as far as I know.
It's connector had the outer insulation become brittle and it broke, the edge of that brittle insulation cut like a knife edge into the insulation of one of the individual wires that make up the MAF's five wire connection but it didn't look like it severed any of the actual copper strands so I broke away the brittle outer insulation and wrapped everything up tight with some of that self sealing silicon tape that 928 Motorsports sells.

I wonder if it isn't that connector, or its wiring sometimes but bending and pulling on it doesn't seem to affect things at idle and driving it after pulling and bending it doesn't give any change to the symptoms either...
Not the most scientific test i know but short of changing out the harness or at least removing and splicing in a new connector what can I do? I don't think you can even buy that MAF connector can you?

Thanks for helping!

the flyin' scotsman

High idle and surging............fuel starvation or excess air/vac leak.

Changing the fuel filter is a good thought..............what fuel pressures do you have?

Did the problems exist before the supercharger install or has it developed over time?

aggravation

Fuel pressure is around 42 at idle with vacuum and around 48 without vacuum. shows just over 50 after shutting down, not sure why that is.
The problem developed after installing the supercharger, I'm guessing I did something or some part got pushed to the edge of it's life by the work or the higher boost.

I've replaced the:
ISV
Throttle Position Switch
Intake removal and replace with new gaskets and vacuum lines (the two hoses on the ISV were kept but they are relatively fresh)
New Flappy and flappy bearings
new O2 sensor
new stock fuel pressure regulator
numerous leak checks with intake under pressure...no big leaks showing although the air in the 15 gallon tank leaks down in about 20 minutes time...sounds like it's going through the cylinders, in fact by pulling the plugs I verified this...
Compression test shows all cylinders good
Spark plugs look great

Probably some other items replaced and tests performed but off the top of my head that's where I stand right now.

Alan

I'm sure you can buy the MAF connector - I believe John Speake even sells them...

Let me know if you can't find them - there certainly are places that sell them: shell, boot & terminals... Try Eagle Day e.g. http://www.eagleday.com/ampconnectors.html

Since you know that has mechanical problems at least I'd fix it as a priority.

Alan

Garth S

Do you also have an in-tank pump? My '88 had one, and two wires dissapearing into the tank can be a dead give away . Mention this, as numerous fuel delivery issues trace to this small pump dying ..... and in its death throes, it can dump junk into the close tolerance guts of the primary pump.
Sometimes, a main pump can be cleared by reversing the wiring for a quick blast ... but only with fluid inside, as the pumped media lubricates the internals.
To test your pump, remove it and clip on a couple of clear plastic/tygon lines into your lawnmower, etc gas can: connect to +12V and test ..... with all due caution to fire safety, etc.

the flyin' scotsman

What condition is the MAF boot?

Given that you changed the ISV and TPS you had the intake off at least once..........its possible to miss a hose or vac line off of the tbody.

aggravation

The MAF boot seems to be in good shape, I've looked it over trying to find a crack or tear by pulling at it and the rubber was still pretty supple, no leaks there.

I have had the intake pressurized a few times and listened with a piece of rubber fuel line as a sort of stethoscope and can't detect any area that has air coming out except at the throttle linkage but not very much of a leak, I'm told it is normal and couldn't create my symptoms.

I've had the car idling and sprayed starting fluid under the intake from numerous angles and there was no change to the idle speed or sound...
I've used small mirrors and even a fiber optic camera lens on a gooseneck attached to a small color video screen to explore all the hose connections under the intake on the ISV and vacuum connections on the throttle body..it all looks connected and clamps on just about every hose...

The only thing I suspect under there is the ISV connector, it seemed to click into place and looks securely plugged in but it was very hard to manuver my big hand under there to plug it in..basically as I was about to give up on the last attempt I managed to plug it in to the socket with just a tip of one finger so I never really felt it "click" in place..but as I said it looks like it's on correctly so it's probably not an issue. I'm not even sure if it wasn't connected could it cause the symptoms I have? Could a bad ISV fail in a way that I'd have these symptoms? fail open..fail closed...I don't know what it would do.

One think along those lines that just occurred to me is the last two times I restarted the car after having the battery disconnected the car acted like it wouldn't idle at all. I had to pump the gas pedal until it warmed up...once I drove it around the block a while it went into the high idle and surging mode again! subsequent restarts with the battery connected don't give that no idle at start up situation.
Maybe that would be a symptom one of you could recognize that will point me toward the culprit.