2004 Express 6.0 won't start

[ALD038]

New to the forum and appreciate any help. History, ran out of gas, put gas in and started and drove home. Next morning started ran rough and drove to end of drive where it died and has not started since. Rented code reader from Auto Zone and it shows no codes, also rented fuel pump pressure tester and hooked into fuel rail on engine, it shows 61#'s at ignition turn on and then drops to 57#'s and holds. When cranking it drops to 53 - 54#'s. Could the fuel pump be bad even though I have good fuel pressure? Even though there are no active codes could the crank sensor have failed? Can it be tested w/volt ohm meter? All fuses have been check w/volt ohm meter. Last thing, if I just keep bumping the ignition switch it almost sounds like it wants to start but does not, if I just crank it it does nothing but turn over. Again any help is very much appreciated.

[brcidd]

You really should check for spark now.....but, go ahead and spray a few shots of carb cleaner in the air intake snorkel and see it if starts and runs for a few seconds- if it runs then dies, your problem is fuel delivery, and your spark is okay... if no running at all- you probably have a spark issue.

[ALD038]

After going back and reading my post I failed to post the plugs were changed, also the engine will run when carb cleaner is sprayed in the intake. I also failed to mention that it has 150,000 + miles on it

[brcidd]

It's at this point in time that I hook up my "fuel pump in a bucket" test pump. I plumb it into the pressure test port and attach aligator clips to the battery. If van runs, then we know FP or FP circuit is at fault- and I can drive it to where I want to work on it.

One last check before condeming FP would be to check amp draw of current suspect FP. Using a DVM in amp mode- attach to FP relay terminal that feeds FP- and measure amp draw- A good strong pump should draw 6-8 amps- bad connections, or bad grounds may only draw 3-4 amps. You should also check voltage aacross the FP connector at the fuel tank. Remember the ground side is half your circuit-- make sure all grounds are good.

You can also pump fuel tank out this way- by plumbing pressure test hose into a gas can.

[ALD038]

Ok, haven't had a chance to get back to the van but I do have a question. If I've got good fuel pressure at the fuel rail using a test gauge what is purpose of hooking up a "fuel pump in a bucket" going to do? I know I have fuel pressure, am I looking for fuel volume? I know by taking #12 fuse out of the fuse block my fuel pump does not run. I can understand checking amp draw on the fuel pump and will do that. My problem is I don't have a fuel pump in a bucket w/o buying one. Just trying to get this thing going w/o having to spend anymore then necessary. Regarding the crank sensor in the original post, is there a test for it? Does it have to be removed in order to test it? Again thanks for any and all help.

[brcidd]

Originally Posted by ALD038

, also the engine will run when carb cleaner is sprayed in the intake.

If they engine runs with carb cleaner, then your spark is okay- you do NOT need a crank sensor if spark is okay!

Your fuel pressure and flow is in question- I know you quoted 61 psi- but perhaps your gage has some error...These can be tricky- they need exactly the right pressure to start. What is your fuel pressure leak down rate? Does it take ten minutes or ten seconds to drop from 61 psi to 0 psi after you turn the key off? If rapid leak down, you probably have a leak either in tank or under intake plenum.

This is entirely why I made my tester (FP in a bucket) to answer these tough ones prior to FP replacement. I always like to be sure before I replace a FP.

[ALD038]

Fuel pressure seems to keep coming up, do you have any suggestions on building a fuel pump in a bucket such as type of pump to get and where to get the fittings and hoses to build one. What pressure do most fuel pumps run? Is there a specific one or a universal one? Thanks.

[brcidd]

If you are going to buy a fuel pump, then I'd buy the one for your van and install it. If van runs, then you are happily fininshed, if van still has issues (most likely not the case) then I'd use the old pump to build my test pump apparatus.

The hoses to use are actually the same as R-12 refrigerant hoses.

The first time I ever tried anything like this, I actually plumbed two vehicles together and ran dead vehicle off of donor vehicle's fuel pump. As long as the use the same fuel pump's spec, it worked quite well. Just neede 10 ft of refrigerant hoses (with depressors in each end) to plumb them together. But, you can't drive the dead vehicle this way....This is just another option, for those with more time than money, and like to be sure they have the problem figured out, before spending money.

High pressure systems are 61-65psi fuel pressure- which is most all present day made GM trucks, Vans, etc....

[ALD038]

Ok, I'll see what I can come up with on the hoses. I know everything is pointing towards the fuel pump but would the throttle position sensor cause a problem like this? Just curious.

[brcidd]

TPS would set a code if it were not sending out expected values...

[ALD038]

Good news, the van is running. The fuel pump was the problem and has been replaced. I want to thank you for your help in getting this thing going.
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