Volvo 740 GL -88 runs uneven minutes after start

740Driver · Post by **740Driver** » 17 Mar 2004, 10:18

Hi!

I'm a guy from Sweden and Car Vocabulary really ain't my thing but I hope you'll be able to udnerstand what I'm trying to say nonetheless.

The car in Question is a Volvo 740 88 with LH 2.2 and 200 000miles.

Alright, the thing is that my Volvo runns uneven the minutes after start. It really doesn't matter if it's been standing out in a snow blizard or if I've been on the motorway for a while and then had it turned off for 15 minutes, it will run uneven nonetheless.

It's not to bad if you're driving constantly in 30mph. The problem is very much notable when it's time to accellerate up to 60Mph. It protests, shakes so to say, and thene, just for a couple of secs, it runns like it didn't get enough fuel...then it starts to run like it was brand new.

Now, it's probably easy to draw the conclusion: "Well dude, this car doesn't get enough fuel".

The problem here is that it only appears the minutes after start, then the uneveness goes away totally, and it doesn't matter wheter the engine is cold or warm. I've changed fuel filter, spark plugs, wires...the whole kit, without any changes.

I've talked to my fellow countrymen but it seems like noone is able to answer my question, so I'm turning to people outside Sweden instead.

Thank you very much in advance!

Volvord · Post by **Volvord** » 17 Mar 2004, 14:28

Very interesting problem. Being as the trouble does not seem to be related to engine temperate, but it could be related to electrical component temerature.

The first items I would check would be all your ground connectons, poor grounds can cause lots of intermitent troubles. I have seen cases when the resistence in a ground wire caused similar symptoms but cleared up when the heat in that poor connection caused the terminal to expand enough to make a better contact.

Second I would take apart and clean all the wiring harness connectors under the hood. Again it sounds like a bad connection.

Finally the trouble could be with the ignition amplifier, hall effects sensor, one of the injectors, etc.

Good luck

740Driver · Post by **740Driver** » 17 Mar 2004, 14:37

Thank you for your reply!

I'll do as you said and go through the connectors when the temperature allows for it.

I was thinking about the fuel relay. Could it be that it acts up before it gets hot or something? I don't know how much the relay will cool off during 15 minutes though.

On the other hand, I don't really know the symptoms of a fuel relay which acts up, I've only heard that the engine might start to run a bit funny due to fuel problems..

Just a thought...what do you think?

Volvord · Post by **Volvord** » 17 Mar 2004, 15:02

Like any electrical component, if full voltage is not available it may not function correctly. This can cause all sorts of weird problems

Definitly your problem could be the fuel pump relay, or even the main fuel pump. The fuel system can easily be checking by monitoring the fuel pressure. Since your are able to cause the car to run poorly consistently when first started the fuel pressure should be asy to test and observe any fluctuations