I've been having an ongoing but intermittent issue with my car. The drivetrain is stock '91 Lincoln LSC (5.0 w/AOD). It has been driving fine for several days. Today it started up and idled OK, but when I accelerated up the hill it sputtered and would not rev past 3500 rpm or downshift. When I back off the throttle, it will idle and will accelerate gently (thanks to the V8's torque) uphill. I suspected the fuel pump and have a test light connected to it. The light stayed on throughout the event (suggesting that the FP is not the issue). This scenario has occurred in similar fashion a few times, then magically it will run fine again until the next occurance. On days when it runs fine, it runs great!

Does anyone have any thoughts or suggestions?

Thanks,
Andy Schor
'91 745 V8

Sure enough, although the fuel pump tested OK it evidently *was* the culprit. Replaced with a known good used one, the car is running fine. Hooked up the old one on the bench and it ran after a smack of the hammer.

Thanks for the input,

Andy

Disconnect, clean and smear a little dielectric grease around on the "10 prong" plugs attached to the back of the plenium, one is white and the other is black. Fords are famous for this connection failing. There was a recall and they added a short extention with better fitting plugs.
Start the car, wiggle the plugs around and see what happens.

Hi guys thanks for responding. It is a stock FI, worth a look to see if the throttle body is sticking. I have changed the fuel filter then R & R'd it for inspection (clean and clear).

It rained here on Tuesday, the car sat outside (wasn't driven) then ran poorly on Wednesday. Maybe this is a red herring, but I thought I'd mention it. Moisture under the distributor cap?

Fuel level between 1/4 and 1/2 full (93 octane). I have considered this possibility. It doesn't seem to happen on a full tank but that could be unrelated. Up or down hills, left or right turns do not seem to have any effect. But...

Today (Thursday) it started right up and ran well. It upshifted at ~5K on WOT. I haven't bought gas yet, so the fuel level is about the same. Well slightly less after a couple of WOT runs ;>)

It has done this in the past as well. Hence the term 'intermittent'. To me it means that nothing is actually broken. It has been quite frustrating. I have a few errands to run this afternoon, will see how she runs and report back.

Thanks again,

Andy

Yeah, I guess it could be weak spark as well. I had a 240 that did stuff like that, but it was clearly linked to wet weather, and it went away when the car warmed up and dried out.

I guess you should start with the basics, and clean all your grounds. Clean electrical connections to the coil. Replace maintenance items like cap & rotor and plugs if they haven't been in a while. Wires, too, if they are old.

Intermittent problems are the worst. I've been dealing with one with a piece of gear at work.

Greg

After driving well this morning, the car had a rough time starting then ran crappy again. I limped it home and switched to the red block ('88 745T with 330K miles) for reliability. The difficulty starting (cranked but not quite turn over, then started but ran rough) might suggest cap/wires/plugs, but why would it run fine then funky? Presumably it will run well again without being touched...then rough again intermittently...

This morning (Saturday) the car didn't start at all. The starter cranks but engine won't turn over. A couple of times it seemed like it was going to start, nope not today. The fuel pump test light was lit, fuel tank ~1/4 full. Now that I think about it there have been a few times that it had some difficulty starting, but eventually caught and ran OK afterwards.

Last summer (in an attempt to solve this same ongoing issue) my mechanic tried swapping in an ECU from a FLAPS, but he said it ran better with the original one which I believe is from the '91 LSC (this was a Converse in-house conversion). Maybe the replacement was defective off the shelf?

I still believe that it's something (relatively) simple, what am I missing?

Possibly tune-up related (plugs/wires/cap/coil)? Is there a throttle position sensor on this engine? Ignition module?

The symptoms are "all or none", meaning that it's either fine or or it's running like crap (not a gradual degradation).

Argh.

Haveyou tried calling Ross At Converse engineering? If you need his number check his website. Also check for proper voltage to the Ford ignition coil and check the coil itself. Historically the these coils were designed by GM and had problems like you describe. check fuel pressure also and the EEC power relay and the Fuel realy operations. Hope this helps.

Even if your fuel pumps are running ok, it could still be a fuel problem. It sounds like a fuel problem. Could also be some kind of spark misfire problem.

When was the last time you changed your fuel filter? That could be clogged, but I thought that when that happened, the symptom is not intermittent.

Is your problem coincidental with fuel level at all? I believe that on the 700/900s, there is a short bit of flex hose from the in-tank pump to the hard line. This hose can get a hole in it, so when fuel sloshes back in the tank, you could lose fuel delivery. Then if you have a full tank, the problems go away. Just an idea.

Have you checked your fuel pressure at all? Do the pumps ever sound different?

Greg

Is your 91 785 with a Ford 302 fuel injected or carb? I assume FI, so check the throttle body to find out why it is not getting enough air when you floor it. If it is a 4 barrel carb, check that the extra 2 barrels are not opening until the throttle is at WOT.

Klaus
--
I still miss my 164 and my 854T. Just driving a V70R :)