fuel pump check valve?

amschnellsten · 10-18-2009, 05:10 AM

I have been having starting issues after the car is warm. I have replaced the cht sender and reference sensors. I picked up a check valve for the fuel pump and was going to give this a try. When I undo the end with the check valve am I going to get doused in gas or is there a trick? What else should i check if this does not help? This is an 84 3.2 and it seems to act like I am boiling the fuel off in the lines when it sits warm. When I start it cold it starts right up but revs and stumbles oddly for a bit. When it is warm it cranks for a long time and then comes to life. thanks for the help

ossiblue · 08:38 AM

Quote:

Originally Posted by amschnellsten

I have been having starting issues after the car is warm. I have replaced the cht sender and reference sensors. I picked up a check valve for the fuel pump and was going to give this a try. When I undo the end with the check valve am I going to get doused in gas or is there a trick? What else should i check if this does not help? This is an 84 3.2 and it seems to act like I am boiling the fuel off in the lines when it sits warm. When I start it cold it starts right up but revs and stumbles oddly for a bit. When it is warm it cranks for a long time and then comes to life. thanks for the help

Before you dig into your fuel delivery system, are you sure it's the check valve? (BTW, I believe the check valve is internal to the fuel pump on your car.)

Have you checked your residual pressures to see if the check valve may be at fault? Your symptom also could be a leaking fuel accumulator which is designed to prevent the "boiling off" of fuel during hot engine starts. Have you checked that?

The cold start problems could be WUR related. Have you checked your cold and warm pressures? Just trying to save you some time and money.

edit: Having read the following post, please disregard if you have Motronic.

GothingNC · 10-18-2009, 08:13 AM

You have Motronic,not CIS correct?
I do not know if your system has a fuel pump check valve.

If so, not much gas comes out since the non-running pump will stop the flow.

Just do it outside, disconnect battery and away from flame (water heater)

How old is your fuel pump and DME ?

kidrock · 10-18-2009, 05:52 PM

you do have a check valve, it screws into the top of the fuel pump. Make sure to disconnect the ground to your battery before starting this job.

After disconnecting the hose from your check valve at the top of your fuel pump, you may have some fuel to contend with. Bring some old shop rags with you and direct any excess fuel towards the rags. You can stick a #2 pencil in the hoses to stop fuel drainage from the hoses. I say "hoses", because IIRC, you will need to remove the pump in it's entirety in order to remove the check valve. If you can R&R the check valve without removing the entire pump, that's a good thing.

Be careful screwing in the new check valve, they are made of cheap metal and will break fairly easily if you crank too hard on them. If you don't crank hard enough, you will develop a small pesky leak which is immediately noticeable when the pump is running.

I don't know if the check valve replacement will be the solution to your problem, though. There are a few bugs that cause the problem you describe.

good luck and keep us posted.

amschnellsten · 10-19-2009, 01:51 PM

thanks for the pencil idea! I am going to give it a shot tomorrow. If this does not work what else should I look at?