Intermittent starting problem old Volvo


#1

original owner of 86 Volvo 740-not turbo or diesel-180k miles. Runs perfect when it starts. For last 2 months will occasionally crank but not turn over. Problem may persist for hours or days and is unpredictable. Then when you least expect, it starts right up. Had it towed to shop twice and naturally started up fine once in shop. Guessed it was fuel pump relay and replaced that, but problem recurred. A perfect work/utility car if I can depend on it but I never know when it will turn over. Do not want to dump lots of $$ shooting blind. Mechanics say cannot help if it starts when they have it. Any ideas or suggestions what to try next? Thanks


#2

If the computer shows nothing, change the engine coolant temperature sensor (feeds the computer). $40 at Advance Auto Parts. It’s been known to help.


#3

I had the exact same problem and I put in a new starter, and found that I was 1.5 qts of oil low, topped it up, and I’ve not had the problem since.


#4

Without knowing if the problem is fuel or spark related, everything would be a wild guess.
Get a can of aerosol carb cleaner and the next time it acts up spray a healthy shot into the intake somewhere.
If it starts up or starts sputtering then you can figure it’s fuel pump related.

If that’s the original pump on a 21 year old/180k miles car, then my money is on the pump.
My opinion is that there comes a point when the pump should be changed even if it’s NOT acting up. Cheap road insurance is the way I look at it.

Fuel pumps can come and go like this; work one minute and quit the next followed by working again whenever it chooses. JMHO and hope it helps.


#5

After starting fine for several more weeks, and luckily driving 600 miles west while moving household, with no trouble, problem finally recurred and volvo is now once again cranking but not starting- for a week. I am definitely not getting spark, having checked that with a plug off. Time for another tow- if it again fails to act up after tow, any more suggestions on what to try next-temp sensor, starter switch, solenoid? Incidentally problem has occurred both in humid midwest and at 8500 ft mountain environ. That help? Thanks.


#6

Have you checked any Neutral/Park/clutch interlocks? How about your ingition switch? An intermittent start problem like this sounds electrical to me, FWIW.