Hello everyone.


I have a 1988 740 wagon naturally aspirated that gives me problems starting when cold. And randomly will cut off.
I have changed fuel filter, both fuel pumps, distributor, harmonic balancer, rotor, spark plugs, wires, catalytic, resonator, muffler and fuel pump relay.
I do not know what could be causing these issues.
I read that the cold start valve, connecting wires, or crankshaft position sensor could be at fault. Has anyone experienced this issue? I also noticed the temperature gauge has an electrical fault causing the needle to bounce although the temp is stable.


Puzzled and confused.... Any help or ideas would be greatly appreciated.


Eric

 

Hard start when cold, the first thing I'd change would be the coolant temperature sensor--I didn't see this in the list of changes.

The random cut off would be the crankshaft position sensor or the fuel relay.

 

Great idea! Inexpensive part when compared to cold start valve. I have ordered both the crankshaft position sensor and coolant temperature sensor. Both parts were less than $100USD including shipping. I will keep the Volvo Forum posted.

 

I assume you realize there are 2 water temperature sensors. One for the gauge and the second one for the cold start function.

 

The dash gauge temp sensor is in front with the cold start function/engine temp sensor in the back and the knock sensor in the middle...all underneath the intake manifold...correct?

 

Yep you have it.

 

Thank you. I need to find the missing part (sensor to dash).

 

I did not know, thanks.

 

I am having trouble locating or identifying the dash sensor. Would you have a part number?

 

Well I had a local mechanic help me when the crank position sensor came in and he told me since I had a 1988 with a distributor that my vehicle did not have a crank position sensor. Is this true?

 

Yes it is.

1988 was the last year they used a "hall sensor" built into the distributor itself to do the job that the crank position sensor does on 1989-92 740's

 

Just replace the distributor which came complete with Rotor and hall sensor. If I do not have a crank position sensor, what could be causing the intermittent stall issue?

 

Bosch 0280130026 for the rear most sensor which is kinda square with flat prong plugs.

Volvo 1362645 for the front sensor which is kinda rounded and has round plugs

 

Not sure. Does the wiring/connection look good for the hall sensor?

 

Mountain740, are you saying you replaced the distributor already and are still having intermittent stalling?

 

Yes. Replaced complete distributor And still experiencing few random intermittent cut off while driving. I cleaned Mass Airflow Sensor also.

 

The distributor was a complete distributor with the list price of $329 and a one-year warranty.

 

By "cut off", you mean complete engine shut off or a stumble?
Does it happen at high speed, low speed, hot, cold?
How do you restart it? Starts immediately or have to wait, or what?
Give more details so we can figure it out!

 

I have driven it the past three days and not had it shut off on me once. Although randomly I could be driving with the car already warmed up and I'll notice the RPMs drop to zero. The car does not stumble but rather loses power. I typically will pull to the side shut the car off and turn it right back on again and it not shut off again for the rest of the day?