Hello everybody.
I'm having a start up issue that is proving hard to diagnose. So before I keep throwing money at it I would like to ask the community.
Its a 1979 242 2.1 3 speed automatic with more or less 90k miles, and when I bought it this problem didn't exist.
It starts perfectly every time when I start it for the first time in the morning, but as soon as I park it for more than 10 minutes, or even a couple of hours, it takes several attempts and lots of cranking for it to start.
And its a bad start, like a weak one, like an tired effort until it gets back to normal running. Once it starts it runs fine, but I'm afraid its going to live me stranded one day, eider by not starting at all or by draining the battery.
It has a new gas tank, I replaced the sending unit and both fuel pumps, new fuel filter, injectors, seal and retainers. Battery is good, it sparks and it gets fuel. Compression is also OK.
I was told that it could be the fuel sending unit, the fuel relay or the ICU unit, but I wold like to consult you all before I check those.
Thanks in advance,
JP

 

A 1979 should have the CIS fuel injection system. If not - let us know.

Hard warm/hot start could be caused by low residual pressure. (with a CIS car)

That happens when the check valve in the fuel pump does not keep the fuel pressure high enough after the engine is turned off.

It can also happen on the other end with the fuel distributor not holding pressure. ( I understand you have a "new" main fuel pump and A new fuel pump check valve should be part of this "new" main fuel pump you had installed)

The next time you expect your "bad start" (or long crank time) to happen -

Every time you turn the key to the ignition position - the fuel pump should run for ~1.5 seconds. If the residual fuel pressure is loo low - the engine will not fire. SO - try cycling key key to the on position a few times to pressurize the fuel system. Then try to start the engine. If it starts immediately or better - your "rest" pressure is leaking back to the gas tank, due to a bad check valve in the fuel pump (most common) or on the other end in the fuel distributor (most expensive!)

Another diagnostic option is to connect the appropriate fuel gauge, and measure line, control and rest pressures. But I doubt few have the appropriate gauge setup today to work with CIS systems. (I don't think I could get any of mine to work on a car that old anymore!)

The car will start better when cold - because the cold start injector adds additional fuel and that will mask the low pressure for the first several seconds that is sprayed from the 4 main injectors until the fuel pressure builds back to normal. .

 

Hi Hoonk,
My car does have the CIS fuel injection system, and my Volvo mechanic has the appropriate fuel gauge. It is at his garage already. I'll let you all know what is result of the tests.

Thank you,

JP

 

a very long time ago I had this problem with my 142, used the same "priming" process

 

Hoonk was correct, it is a fuel pressure issue. Thank you.
Now I'm looking for a "fuel pressure control valve" or "warm-up regulator", and they are expensive!!!