No Start/Fuel Pump Diagnosis

[Mic1980]

Well i just grabbed a fuel pressure tester kit from Harbor Freight not sure if I'm going to do it today since it's getting dark. As far as the psi on AllData I could have selected the wrong year like 95 model and came up with that figure.

[Mic1980]

Ok.....so today was a busy day for me however I did attempt to check the fuel pressure. Now the fuel Pressure test kit I bought at HF is this one: http://www.harborfreight.com/automot...ter-92699.html unfortunately it started to leak on me and then fuel got into the gauge. It did not leak at the fuel test port valve but at the top with teflon tape or pipe threading compound.

Even though the kit malfunctioned I did get to get some type of reading. The first turn of the key the system wasn't pressurized so it ended up around 30ish the second time it was within spec between 60-66psi and it did hold steady within 56-60psi but that is when the leak showed up and it slowly started to decrease in pressure so I'm going to try to repair the guage and give it another shot to see what happens.

Note there is another thing that I didn't mention. I noticed the fuel in the tank was pretty dirty like brownish. The fuel is fairly new less than 3 weeks old.

[old_master]

Take it back and try another one. You know there's a problem with the gauge, so you can't trust it to be accurate.

This is a pretty decent tester and most auto parts stores have them:
http://www.amazon.com/Actron-CP7818-...ds=actron+fuel

[Mic1980]

Well I took the rubber round protector off this time I used a lot of teflon tape and used two wrenches to tighten up the tester. I had to really tighten it this time and it worked not 1 drop of fuel dripped from the connections. I also made it easier by removing a few things so it could have it's own resting space.

Anyway I did some readings. The results were good when the pump was priming for 2 seconds every time, it was like 64psi, but when I turned the key off or if I left it on it would hold between 55-58psi for 20 seconds maybe 30 or so and then it would slowly leak down. Another thing to note is the psi would drop quickly to 10 psi this happened only twice but when I tried to create that symptom again I couldn't do it.

I'd rather grab one at sears for 32.00 then wait for the shipping I need this car out of my front house thanks for the link though I will notify my brother about that tester anways.

edit: I was thinking about my situation and if I had a bad pressure regulator the blazer would run bad or stall sometimes but with the readings I'm getting that is enough to start the car.

[old_master]

Agreed, regulated pressure is OK BUT, the leakdown is a problem. Next step is determine what's leaking. Could be an injector, a poppet valve, the regulator, a line inside the plenum, fuel pump check valve, the line from the pump to the module etc. The fuel pressure tester needs to be modified so it connects directly to the fuel filter. All fuel pressure and flow must end at the tester, (no fuel can be allowed to reach the plenum). Key ON, (engine obviously off), fuel pump running, pressure must be 73psi to 108psi and must remain above 55psi for at least 10 minutes. The results from these 2 tests will determine if the leak is in the tank, or in the plenum.

[Mic1980]

Mr. Old Master I seem to have ran into another bump on the road to getting this POC vehicle to a starting state. I went to go pinch the flex part of the fuel line and read the fuel line pressure which is after the fuel filter and my fuel pressure tester died so I'm getting it replaced tomorrow. I couldn't modify the tester to fit onto the fuel line I just didn't have a big enough fitting for it so tomorrow when I get a new one I'm going to check the intake side of the fuel supply line and see if there is a leak.

[old_master]

Pretty simple to make an adapter that will connect to the fuel pressure tester. Disconnect the quick connect fitting from the fuel filter. This fitting will connect to the filter: http://shop.advanceautoparts.com/web...line+connector From that fitting use a piece of 3/8" fuel injection rated rubber line and put one of these in the other end of the hose: http://www.tuxedoparkbrewers.com/ind...roducts_id=775 Then attach your fuel pressure tester to the 1/4" flare fitting.

[Mic1980]

I'm a little confused, my fuel filter doesn't have any quick connects. I don't see how that Dorman universal connector would work or connect since the fuel filter is a threaded female.

[old_master]

In that case, substitute the quick connect fitting in the previous post with this one:
http://shop.advanceautoparts.com/web...el+line+repair

It already has the barb, install the rubber line and the adapter and you're good to go

[Mic1980]

That'll work.

[Mic1980]

I got the new fuel pump tester kit I had someone who works close by HF bring it back for me. When I opened the new box I could tell it has been used there was two tiny little scratches on the glass and the insert part of the gauge had green oxidation on it. I still gave it a try and when I turned the key the needle didn't move I tried 2 more times and then finally it jumped up to 10psi so I kept cycling the ignition to increase the psi because that was the only way I could get the psi to go up. I got it to 54psi and it wouldn't go further. I paid attention to the leak down and it wasn't holding either. I can't go by the readings off this tester so I'm going to get another one since it's been paid for and possibly a different brand kit as well. The one good thing was that the gauge didn't leak at the connections this time, you really have to put a decent amount of tape it's not like air tools.

[Mic1980]

Well today I finally got to test the fuel pressure right and for the FP prime I got 61 almost 62psi and when the prime would stop the needle would jump to 54psi and it would slowly leak down a number every 10-20 seconds. I still think I have enough psi to start the car but there is definitely a leak somewhere. Tomorrow I will isolate the leak. I'm starting to think this might have something to do with the injectors, I don't see anything else stopping the car from starting up.

[old_master]

Leakdown is excessive, 10 minutes after the pump shuts off, the pressure must be 55psi or more. Check the fuel pressure and leakdown at the fuel filter and post your results. If leakdown is excessive in the tank, the cause must be repaired in order to diagnose any other leaks.

[Mic1980]

Ok I finaly got around to checking the pressure at the fuel filter. I have pictures of the adapter. So with the key to the on position and engine off the PSI reading went to 100PSI and a little bit over. It held at 100PSI for a few minutes within 10 minutes I'd say the PSi stayed over 95PSI and in 20 minutes it stayed at 90PSI. I bought these fuel pinch clips http://www.google.com/url?source=img...Epay8csg_HaKCw

Tomorrow I'm going to check the other side of the fuel line from the fuel filter to the spider and regulator and see what happens I think I have a problem in the intake area.

[old_master]

Nice job with the adapter!

The fuel pump is fine. The leakdown is in the plenum. Pull it off and have a look around. After the plenum is removed, you can reinstall the fuel lines to the metering block, activate the pump and look for leaks, possibly the regulator. If you can't see any leaks, either an injector is leaking or the regulator is leaking internally. Either case, might as well do the injector upgrade, it comes with all new injectors and the regulator. Post your results.