Won't idle & hard to start hot

[Paul Valcourt]

Help. I have searched the forum and there is a lot of information on this topic in various bits and pieces but none that encompass all my problems without a lot of reading. I have posted this to try and get comments on the issues below.

Stock 75 2.7

On Cold Start
-starts easily but will only idle at 500-600 RPM (should be 1,800)
-requires hand throttle to hold at higher RPM

During Warm-up (after 3-5 min of running)
-will hold idle at around 1,000 RPM

At Operating Temp
-will not idle and stalls
-runs rough below 2,500 RPM
-hard to start

Other Signs
-tachometer jumps around occasionally
-driver has a halo but it disappears while pushing car out of traffic

I have not done any type of checks yet. I do have a copy of the CIS trouble shooting guide that I will use once some comments have been put forth.

[Joe Bob]

Sounds like more than one problem....Warm Up Regulator, Fuel Pressure and maybe the check valve that screws into the head of the fuel pump.

WUR is the likely culprit on warm up....as well as the cold start injector....

Hot start could be fuel bleed off caused by a missing or worn out check valve.

The fuel pressure should also be checked. CIS likes a LOT of pressure. Less likely but also a culprit would be the accumulator...bring bucks for that piece....

Good Luck.

[vash]

paul, do you have the CIS testing gauges?

[Paul Valcourt]

I do not have gauges specific to CIS testing. What are they? Are they special gauges only for use on CIS testing?

[Porsche_monkey]

Check the AAV. Does it have voltage when the car is running, does it shut-off the air bypass when it's warm.

[Paul Valcourt]

I have not checked the AAV, not sure what it is so I will have to read my Haynes manual. The car is located about an hours drive from where I am so I won't be able to start checking things till this weekend. I was looking for some direction so I wouldn't waste a lot of time checking everything. Thanks Mikez, Unfixed and PBH for responding.

[Porsche_monkey]

Pinch off the hose to the AAV when the engine is warm. If that affects the idle then it is not working properly.

You're probably hung-over after last nights celebration, right?

[Randy Webb]

First, do a complete tuneup, valves and ignition. Also check out the CDI box if you can. This is liable to be a big effort due to the wide variety of problems. You want to eliminate the easy stuff first.

Then proceed with the initial CIS checks, then the rest. Good luck.

[Paul Valcourt]

PBH - yeah a little bit. My apartment is right downtown Calgary where everyone gathers, honking horns and celebrating after each win. They were going late into the night after yesterdays win. I'll try your suggestion this weekend when I get home.

Randy, I just did timing, wires, plugs, rotor, cap and valve adj. The CDI box seems to be working ok.

[Randy Webb]

OK, Paul. I wish you good luck - I've removed CIS from 2 engines so far....

The yellow Bosch book is great for genral explanation of the system. Keep notes so you'll know which of the many subsystems you have tested or replaced. And CIS needs good fuel pumps (and their pressure) but your symptoms sound different.

[Paul Valcourt]

Update, I picked up the CIS gauges but never used them. A friend told me to check the coil as he had a similar problem with a carburated Dodge. I put on a different coil and it now idles at operating temp and starts hot no problem.