Baja

If you install a clear line or clear filter after the LP, make sure it can take the pressure.
Since you have replaced the hard lines up to the LP, I would install a clear line or filter there, where there is suction, not pressure. Keep moving it around until you find the source of bubbles. I think your mechanic is right.

infidel

Even with a stock plate sliding it all the way forward can cause the governor arm to get stuck under the plate. You should either slide the plate back about 1/16" back from full forward or follow the instructions here http://www.pdrdiesel.com/oldsite/TechLeverAdj.htm

Dhorn33

So if this is the case would it cause any of the problems I have described?

infidel

Not really but it should be corrected or your egts can go sky high.
I'm still thinking something's clogged up in your fuel supply system.

Dhorn33

Tonight I unhooked the fuel lines from the tank - and put them into a gas can with diesel fuel in it. I started the truck and ran it using the cas can as a fuel source. The truck ran exactly the same with the exact same fuel pressure and problems.

Next I pinched off the return line with a vice grips - and the fuel pressure jumped from 18 to 64 psi - doesn't this indicate that the new overflow valve that I installed is bad? I grabbed the old one - and messed with the spring again and reinstalled it to get a fuel pressure at idle of 30ish psi. If I give it throttle with no load the fuel pressure drops.

I am going to contact the vendor that I got the overflow valve from and see about getting a new one sent out.

Josh - I wonder if someone around here has one that they know for sure is good so I can do another test with a good one and see what happens? I think this test tonight indicates that there is not a problem with the tank or the pickup - it must be either the lift pump, fuel heater or something up there. My local diesel shop suggest I bypass the fuel heater so I may try that next I guess?

Just so I am clear on how to do this bypass of the heater -

I have to remove the short formed rubber hose that goes from the lift pump to the heater - and replace th 90 degree brass fitting on the lift pump with a male 1/2" npt pipe fitting to a 3/8" barbed fitting. Next I need to remove the rubber fuel supply line from the hard line on the backside (toward the cab and on the engine side) of the filter housing and put it on the new barbed fitting that Iinstalled on the lift pump. Do I leave the line open that was running behind the filter down to the heater and the other one that I removed the formed rubber hose from?

If I remove the heater and pre-filter from the system is there any worry about the lost filtration that the pre-filter was providing? Is there any negative side to removing this from the system?

Dhorn33

Mmmmmkay.



Last night I heard the weather forcast was predicting rain and maybe even snow - so I decided to go back outside at 11 pm and hook the fuel lines back to the diesel tank and reinstall the filler neck, etc. since the turck was in the driveway with the fuel lines sitting in a gas can! Fast forward to this morning....



I started the truck and went on my way to work. The truck was idling at 36-38 psi. Then I started driving and it stayed pretty constant at low throttle - and if I hammered on it it would drop to 10 but immediately go back up to 38 if I let off. After few times messing with it - it seems to have gotten to an idle psi of 22-24 - and if I rev to 2500 psi with no load it goes up to 32-34. If I drive it will stay around 20-22 - unless I hammer on it then it drops down - sometimes to zero - but immediately goes back up when I let off. It is running MUCH better and I never got to the point where I could get it to stumble or blow any white smoke. ***???



This is with my original overflow valve with the spring at approx. .5". I am really starting to wonder if this **** overflow valve isn't the source of these problems? This is absolutely driving me nuts!

Fueling around

The more you peel the onion and describe conditions it tells me to replace the lift pump.

Your pressure is exactly what I saw on a 98 12 valve. Never a problem starting, but did have a little lack of zip and a slight tick. Did a static pressure check and it was low, but still within range at idle and at 2,000 rpm. It was already on a chassis dyno so they did a dynamic pressure check. Pressure was good at idle, but dropped very low on a dyno run.

Remember, pressure is only half of a pump characteristics. Flow is required to feed the injection pump AND sustain pressure.

Dhorn33

So tonight after work I was driving home - and the truck was running perfectly. The psi at idle was 22-24 - if I throttle it would build pressure and was 32-36 when I was on it - and the pressure was going up when I gave it fuel instead of down. I am very, very confused. I think maybe there is something in the system blocking flow or maybe a sticky check ball in the LP. The truck ran great - with normal pressures.

I actually stopped by Triple D Performance in Coon Rapids, MN and had wanted him to check it out- but it was running perfect the whole way there? Anyway - Josh had an extra LP in his box so I may swap mine out, bypass the fuel eater and see how it works - if the truck stops running like it did tonight. Craziness?