My '90 has been running a bit weird lately. Initially I was losing power just a bit while cruising at ~ 40 mph.

Today I pulled the car into the driveway to check some things, I just let it idle for 5 minutes while I listened to the in-tank pump via a length of hose stuck in the filler spout. The engine began running rougher and rougher almost stalling only to catch again. It did this for 1 minute or two and then it stalled. The engine will 'catch' whatn I try to start it back up only to stall a second later. It will run (rough) if I keep my foot on the gas.

I have:

*cleaned the throttle body and checked the tps switch. (clicks right when you move the throttle)
*Inspected the main air hose from the AMM to the throttle body (looks good)
*Disconnected and reconnected the AMM
*checked and cleaned fuel injection related fuses
*In tank pump sounds strong
*Main pump sounds strong.
*can't check discharge from the fuel pump relay, but I did hear fuel rushing back into the tank when the car was running and I was listening to the intank pump.
*removed and cleaned IAC valve, bench tested with 12V and it appears to work.

So basically I'm stuck where the car will start as normal, ramps up to 1000 rpm and then just dies.


Other Possibilites:

Fuel system relay (replaced 60k ago)
crank position sensor (might be 230k old)
coolant temp sensor (idles when cold but not when hot)???

Thanks in advance for all responses.
Matt

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'90 245 224k, '93 945 184k

Purrs like a kitten at 1000 rpm with the AMM disconnected. - but dies when I try and give it gas.

failed AMM???

M


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'90 245 224k, '93 945 184k

Did it purr like a kitten before you disconnected AMM? If so it is probably the AMM, do you have a spare?
Pull fuse 6 for a few minutes to reset codes and see if the same ones come back.

Dan

no, definately not... wouldnt even run before I disconnected the AMM. I dont have a spare but there are a few on ebay right now for ~ $50 buy it now. I'll pull fuse 6 and report back.

Thanks !!
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'90 245 224k, '93 945 184k

...That's only for '91 and up, when Fuse 6 replaced the underhood 25A fuse.

But pulling that fuse for a few seconds should do the reset.

Hope the AMM fixes things for you, but I would also replace that old CPS, just due to it's age and the trouble it's known for with age.
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Bruce Young, '93 940-NA (current), 240s (one V8), 140s, 122s, since '63.

AMM failed. You might try some electrical contact cleaner on the AMM connector and keep your fingers crossed. I sent you an email.
Dan

I tried the AMM cleaner on my bad AMMs. It did make them a little better, but definitely didn't fix them. I've had some in the past that just failed "a little bit" and I bet the cleaner may have fixed them, but for one as failed as yours, I doubt it will help. If you have the MAF cleaner, give it a try, but I wouldn't spend the 6 bucks on it if I were you.

Disconnect AMM with key off and then start it, if it idles fine the AMM has failed.

Look at the base of the CPS is the insulation frayed and disintegrated?

Make sure 25 amp fuse near the battery has good solid corrosion free connections at the fuse and battery.

Check for codes on the OBD module on the rear of the passenger front wheel well.
Dan

codes are

312 knock sensor I think

231 lean or rich
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'90 245 224k, '93 945 184k