Inline fuel pump

Hello,

Double check the electrical connections. A lot of times they can back themselves off if you are using ring connectors and nuts on a threaded post. Also double check the ground. Make sure all the paint is scraped off where the ring connector screws down to the body, making a good, tight, metal to metal connection. Also, make sure that the pump is as close to the tank as possible and as low as possible so that gravity feeds the pump so it doesn't have to pull the fuel out of the tank.

Thanks,
Alex
2CarPros

Well fuel pump is working . it is bogging down but it seems like the timing belt might have jumped. Could any sensor that is bad cause it to advance or retard?

It is a 1986/Volvo 740GLE non turbo.

Hello again,

Yes there is. If a knock sensor was to get a short to power, then the Powertrain Control Module(PCM) would interpret this as an engine knock and would retard the timing to bring the engine back away from detonation,, but it would also set a Direct Trouble Code(DTC) and your vehicle's Malfunction ndicator Lamp(MIL) would illuminate. Is your vehicle's MIL or "check engine" light on?

Thanks,
Alex
2CarPros

No check engine light on. I did try to adjust timing a bit and now I had to move way past my original mark. I was reading that if knock sensor goes bad that it would get stuck in retard mode.I have a 1990 Volvo I'm changing head gasket on right now. I might switch out knock sensor just to see if that is the problem

Hello again,

Is your Malfunction Indicator Lamp(MIL) illuminated? If your vehicle's knock sensor was shorted to power if would set Direct Trouble Code(DTC) P0327 or DTC P0333 and illuminate the MIL "check engine" light. Get back to us, please.

Thanks,
Alex
2CarPros

About to swap knock sensor. There is no check engine light on. It could possibly be my maf sensor. Before this, car would idle but dir when I'd press even a little on accelerator. Put maf sensor from a 1990 Volvo 740 turbo I also have and car ran good for around a week. Could it be maf cause its from a different year?

It's a 1986 740 gle and there is no obd unit in engine bay

Hello,

The MAF from the turbo should be just fine for the naturally aspirated vehicle. It would be a problem if it were going the other way around. I would double check the timing belt. It might have jumped a tooth or two.

Thanks,
Alex
2CarPros

I did check belt and can gear mark lines up on mark on rear of cover at the same time as crank shaft pulley mark and zero degree mark on rear cover.

Hello again,

How about the cap and rotor?

Thanks,
Alex
2CarPros

Checked cap and rotor, they are fine. I'm kinda thinking maf because when. I unplug it while car is idling real rough, it smooths out as soon as I unplug it. But will die if I attempt to push the accelerator.

Hello again,

Okay. Mass Airflow Sensor(MAF) is probably the most important sensor on your vehicle. Your vehicle's Powertrain Control Module(PCM) uses the signal from the MAF to determine the amount of air entering the engine for it's baseline fuel map so it know how much fuel to add to maintain the proper Air:Fuel ratio. The MAF circuit is a complicated circuit but basically breaks down to a thin platinum wire that the circuit passes electricity through it. The resistance of the wire heats the wire to around 500 degrees. As the air entering your engine cools the wire, more electricity will have to added to maintain the 500 degree temperature. Your vehicle's PCM can now measure by the amount of electricity added to the wire the amount of air entering your engine and go it's proprogramed map to add the correct amount of fuel. Sometimes the wire gets dirty and skews the MAF sensor. Here's how to clean it.

https://www.2carpros.com/articles/mass-air-flow-service

Please go through this guide and get back to us with what you find out.

Thanks,
Alex
2CarPros

I've already used maf sensor cleaner and didn't work for me

Hello again,

Here's how to test the MAF sensor on your vehicle. I have included the diagnostic test procedure in the diagrams down below. Please go through this guide and get back to us with what you are able to find out.

Thanks,
Alex
2CarPros

Would it be possible to and me link to where you got the diagnostic information from?

Hello again,

The information is from Mitchell 1. I believe you would have to buy a subscription to use this service. I think there is a link on our homepage for you if you so desire.

Thanks,
Alex
2CarPros

Also, thank you for the information on diagnostics page. Another question, where is the thermostatic air cleaner door located on my 1986 Volvo 740? Is it before the air filter box?

Hello again,

I have included the information that you requested in the diagrams down below. Please go through it and get back to us with what you are able to find out, or if you have any other questions, please feel free to ask. It's why we are here.

Thanks,
Alex
2CarPros