Volvo Repair: 1990 740 gle, mass air flow sensor, mass air flow

Question
QUESTION: my mass air flow sensor was bad and I went to the junk yard and got one off an 88 volvo, this one had an adjustment screw unlike the one off my car. I put it on anyway and my car ran much better.....until a few days ago I drove about 35 miles on the highway and it just stalled, it started after a while and I made it home then drove it to work , it stalled every 3 minutes could i have messed up my car by putting this other part on my car? now it doesn;t want to start maybe for about 2 seconds or so. could it be fuel injection relay?

ANSWER: Denise, Did you check the number on the meter?  Im pretty sure that a 1990 is a 016 whereas the 1988 is a 007.  These meters  are NOT interchangable.  I would find a 016 meter first.  It may be a relay or it may be a fuel pump check valve starting to go bad.  Roger

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QUESTION: what is and where is a fuel pump check valve, I replaced the relay but my volvo is still giving me problems. I was on the freeway this morning everything was fine then suddenly it just stalls, I put it in neutral and starts up again but right after I put it in drive engine bogs down and cuts off, eventually wont start at all

Answer
A fuel pump check valve is on the fuel pump.  It holds pressure at the injectors.  This is starting to be one of those things that I would have to run a few tests on and check things.  Do you have a good volvo shop that you can take the car to?  If not, where do you live?  I may be able to help you find one.  Roger