The other day I bought an '89 coupe with 73,000 original miles. It is just pristine inside and out BUT...it hasn't been driven since 2007. PO said they had just completed changing out the water pump and it had been driving fine, then it started missing and barely made it home. It has sat in the garage since then.

I drained the tank, changed fuel filter, put in fresh gas, and changed out the rotor. The engine started right up but idled rough for about 1-2 minutes and then died. It would not re-start and seems to crank over slow on re-start attempts. After it cools down (sits for several hours), it will start right up but only for a couple minutes and then she dies again. Any ideas where to start? My Chiltons doesn't seem to have much in the way of trouble shooting for the later HEs and nothing on Martelli ignition.

Can these engines run on ONLY the cold start injectors? If my main injectors are somehow not opening, is it possible that the engine would run only until the cold start is cut out? Any help is appreciated. Thanks.

 

Yours doesn't have cold start injectors. Those were deleted circa 1984.

One thought is "overfueling". A dead cold engine would enjoy a very rich mixture on start-up and for a minute or two....but then be unable to tolerate it.

If you sense that might be the case then I'd check the coolant temp sensor for the fuel injection (aft of the left thermostat) and also check for excessive fuel pressure....which means cutting open a fuel line to tee-in a pressure gauge (not as bad as it sound but you then need to replace the fuel line).

If you have an ohm meter we can look up the specs for the temp sensor. Or, just remove the connector and jump the contacts inside the plug....which approximates the reading for a fully warmed-up engine.

Others will chime in with other ideas. I'm still on my first cup of coffee :-)

Cheers
DD

 

Doug, Thanks. So no cold start injectors well, one less thing I checked the Coolant Temp Sensor: Pulled connector and measured resistance at the sensor (open circuit); then started the engine (started right up as usual) then jumped Coolant Temp Sensor at plug (RPM increased noticeably, it would run pretty smooth for several seconds then RPM would drop, then it would pick up and run smooth again; just kept cycling. In the end it ran for maybe three minutes and died and would not re-start as before.

Then I measured the resistance at the sensor again. Still an open circuit. The coolant manifold?? was warm to the touch but not hot. Does anyone know at what temperature it is supposed to close the circuit? It could be part of the problem but apparently not the whole problem. What next??

I am still looking for fittings to make a fuel pressure testing "T" so fuel pressure is unknown for now.

 

Lots of crud sitting in the fuel dashpot beneath the battery. Clean out and replace the sock filter over the pick-up. Just my UDS 0.02.

 

The coolant temp sensor is a sensor not a switch. If you have an open circuit that explains your over-fueling. The temp sensor will alway have resistance. it just varies with temp. The resistance drops as the temp goes up. Replace the sensor.

You spark plug are fouled because of the rich running. The fouled plugs are causing the engine not to run properly. Put a set of fresh plugs in the car after replacing the temp sensor. If you can drive it the plugs might clean up. Make sure you gap the plugs as per the manual. They will come with too great of a gap. The ignition systems on these cars are not like modern systems and need the small gap to work properly.

I would also clean and adjust the throttle plates and linkage. Then once you get it fully warmed and idling good change the oil. If you have already done that do it again. The rich running condition will cause the crankcase to have tons of fuel in it.

Don't forget to check and set the timing unless it is a Marelli car.

 

Doug and Greg,
Looks like you nailed it. When I jumped the CTS, it wasn't a tight connection so car would run, then try and die for a second, then run again. When I wiggled the jumper, it would die. So seems to be the problem. I will get a new TCS today and see what happens.

I will follow up with the plugs and oil change. Thank you for the great advice.

I have follow-on questions that I will post as separate issues.

 

Glad to be of help. If the connector is not fitting tight you really should replace it along with the CTS.

 

Greg,
As you predicted the oil was heavily contaminated with fuel. It still idles and runs a little rough and seems to me to still be rich, but at least it stays running. I am wondering if in addition to the plugs, the O2 sensors could be fouled. Any tips on good "plug-in" replacements? By that I mean ones I don't need to cut & slice. Thanks.

 

If the O2 sensors are dead the vehicle will run rich. Low voltage means lean mixture and the ECM will adjust fueling richer.

I prefer not to use the cut and splice universal ones either. I usually buy these type of things from RockAuto. A quick check shows some for you car pretty cheap.

 

I changed the rear six plugs today before running out of energy and daylight. They actually looked to be in pretty good condition: I would say almost new BUT...all six had gaps in excess of .040" some over .045". Looks like they were either set that way or not set at all.

One plug had obviously been skipped on the last tune-up (different plug and more wear). Only one showed much in the way of carbon build up.

I was wondering how someone could fail to do such a simple and important task. I mean lets face it, it takes some doing to just get them in and out so I'd expect anyone with the tenacity and skill to do that to go the extra "inch" and gap then correctly. That said, when I asked the salesman at O'Reilly's what to gap them, they told me...wait for it... .052" !! Yikes!

I will get the front six tomorrow. Wish me luck.

 

Hopefully you did not listen the the part store gremlin and gapped them properly. It does not surprise me that you found at some point a PO replaced "most of" the spark plugs. While you have the wires off and they seem flexible and in good shape measure the resistance to make sure they are actually good. You should measure 1000 to 4000 Ohms per foot. If one show open circuit it is no good. The V12 is very hard to tell when you have a misfire.

 

Greg,
No I didn't listen to the parts store gremlin. In fact I only asked to see what answer I would get. I have tried to read through Kirby's book before I do anything too stupid. So I carefully gapped plugs to .025". I noticed my new plugs came gapped at about .040 so I suspect the PO or his mechanic just put them in without setting the gap.

I finished the front six today (boy is my back sore). Now she really runs smooth although I may need to adjust idle downward a bit. I see the rubber bushing on the throttle shafts (both sides) is deteriorated so guess I will be looking for those parts too.

Other problems, other posts Thanks for the help.