Hey all, I haven't been on here much and just realiszed I am a user, using this forum for knowledge and only coming on here when I have a problem or question, sorry!!!

So heres my problem this time.

My rebuilt motor was running well after help from FrankR, conner, and everyone else who helped in this thread. http://www.4x4wire.com/forums/showflat.php?Cat=&Number=790870
Well it was running god for about 700 miles then it starting having problems.

Everything seamed fine when driving on the highway the other night coming home from work but when I got to the bottom of the ramp the truck idled really low and almost wanted to stall. I gave it a little gas and luckily the light changed in my favor so I continued home, everything felt good except after a few seconds of sitting at idle the idle dropped and felt like it would stall. when I got home I let it idle for about a minute to a minute and a half and it did eventually stall.

I restarded it and it did it again, after a minute or so of low bad idle. so I was thinking the AIC vavle was probably not working to hold the idle where it should or something. I then tested it and the numbers were as they should. I restarted the truck and it ran fine for a few minutes, I shut it down thinking whatever it was went away.

The next morning I went to work, and everything was working like normal, the idle when cold was about 2000 RPM's an again I was thinking it was and IAC issue, but it has been this way for a while and I cleaned the iac twice. I went to work and it was driving well then I came to a stop at a light and it stalled within a few seconds of stopping. I restarted and it was hard to restart, and I had to keep giving it gas to stop from stalling, when I left the light it was sputtering and not accelerating much at all and then stalled while driving, after another hard start I attempted to get it out of the left lane but it stalled again and wouldn't restart at all, this made me think fuel issue. I pulled the plugs and attempted to trun the motor over and wasn't getting the blowing out of fuel like I did before when troubleshooting the issue right after installing the motor, which backs up the fuel issue idea.

I added about 5 gal of high test and fuel sstem cleaner and still not coming out into the cyl's like before. I can't hear the fuel pump when my wife turned the key to on or when attempting to start, but heard it after she stopped trying to start, I assume it was running when she was trying to start the truck and I couldn't hear it over the started spinning the motor.

I pulled the fuel filter and it wasn't clogged, and if it was it wasn't too bad, I could nblow through it with almost no restriction. I put it back in and there was no change it the amount of fuel I could perceive through the spark plug holes and still not start. I got a new fuel filter anyway, and will try that this weekend, and wonder what anyone else might think...

I know you don't want to hear "could be"s, but if the fuel filter doesn't fix it (and it might), I'd be suspicious of the fuel pump. Check the entire length of the fuel line for a leak or a hole. I'd also make certain there's a good fat ignition spark. If you're still convinced it's low fuel pressure, suspect the fuel pressure regulator.

Oh - check all of the vacuum lines for leaks.

Start with those and post the results.

Frank

Have you checked your air filter ?

No, but it only has 700 miles on a new filter so I wouldn't think that would be the problem. Besides would a clogged air filter cause it not to start?

FrankR - Thanks for the input, I am hoping it isn't the fuel pump, is there a way to check it? I guess when I take the filter off I can have someone turn the key on and see if it pumps...

Also, the FPR might be a problem if it pumps fuel and has a new filter, is there anyway on making sure it's working properly? Oh and does anyone know how much the MD998700 and MD998753 might cost so I can actually check fuel pressure? Those are the adapters my manual says I need to hook up a fuel pressure gage... If I don't need them what has everyone else used?

If it's fuel related, I would think you should be able to shoot some of that starter-fluid-in-a-can stuff into the intake and it should fire up and run.

I had similar (but not exactly the same) problems that I thought were fuel-related. After a long diagnosis with a mechanic we determined the problem was a cracked distributor rotor that was providing a ground path for the spark. Might be worth checking your distributor rotor. If nothing else, it's a quick check... <img src="/forums/images/graemlins/kewl.gif" alt="" />

Good luck with tracing this down!

Eric W.

For a low cost fuel pressure setup I used an older oil pressure gauge.(after market underdash style)I am sure you must have an old one of those around, or can pick up one cheap at the autowreckers. Hopefully in 5psi incriments or close to that. Then take it to the auto store and ask for some 1/4 plastic air line, 6ft or so(used in larger truck brake system) and some compression fittings to connect to gauge. I am not sure if the Monty has push on hoses or not but you need to some how "T" into the supply to the rail anywhere between the pump and the injectors. The brass parts for the connections may cost you a little now but you will have one for ever and it won't cost $300 like the professional ones. <img src="/forums/images/graemlins/cheers.gif" alt="" />

The fuel rail adapter for checking fuel pressure is available from parts houses like PepBoys, but it must be ordered from the manufacturer. At one time I had the manufacturer's name and crossover part #, but now can't find it. You might check with NAPA or PepBoys.

Frank

The fuel rail fitting on the 3.0L is a special fitting that requires an o-ring for a seal. The adapter goes between the hose fitting and the receptacle fitting on the rail. If you have access to a fuel pressure gauge, there might be an easier way to test rail pressure than finding the rail adapter..... get a fuel supply hose from the junkyard (or a new one from the dealer), cut it in the middle and install the required fittings to connect the gauge. Then you can test the pump by clamping shut the return line to the tank from the fuel pressure regulator and see if the fuel pressure rises to 70psi or so (with the engine running at idle). If it does, the fuel pump is probably ok. When the clamped return line is released, rail pressure should drop to ~38psi. If it drops lower, the regulator is faulty. The modified hose could be left in place for future use, but you'd want to make certain it was well sealed/clamped so there are no fuel leaks.

MMC didn't do home mechanics (or even techs) any favor when they didn't design in a fuel rail test port. It would be fairly simple to add one when the fuel rail is off the truck.... cut the crossover pipe and install a tee fitting with a test port... extend it far enough so it's accessible when the engine is back together and it would then be simple to diagnose fuel pressure issues. I think it would be a very worthwhile change to our trucks.

Frank

I don't like throwing parts at a problem in hopes that I stumble across the solution on the first shot, but sometimes it's less aggravating than testing if the correct tool isn't available. When I do throw parts at it, I make certain to get my mind right about wasting the money before I install the part and exhaust every other test I can think of to eliminate other parts so I arrive at a short list of suspects before I open my wallet. Sometimes I get it right on the first try, sometimes not.

The dealer price for a regulator is about $75 and it's the same at most parts houses for aftermarket units from Bosch, Sorensen, etc. RockAuto has it priced at around $55. If you really think it's the regulator, balance the price, time and effort required to replace it against the price, time and effort to locate the test tools to diagnose it. Then call the dealer (or an independant shop) and ask them how much they would charge to test it for you (without cutting your fuel hose).

You might consider it less of a hassle to replace it and take that off the list of suspects, but be prepared to waste the money one way or the other.

Frank

When it is about to die, how does the exhaust smell? Is it a gassy rich smell, or an acrid lean smell? Have you looked at the tank screen on the pickup? I'd run some fuel into a clear container from the disconnected filter and look for water in the fuel, and I'd hook up the filter backwards and flush it into the container to look for lots of debris.

I think you either have a fuel supply problem, or some electronic component is failing under heat, or there's and electronic or mechanical spark problem, and would diagnose in that order.