Engine/Transmission (1994 - 1998) low boost

[jheath]

I've got a problem I think I have had for awhile. I installed my boost guage a couple of weeks ago, but first I used it for a fuel pressure reading. I had 18 at idle,24at 2000 in neutral. I then moved it to the manifold. I had an average of 10psi max when I ran through the gears normally. I could open it up through the gears and get a max 26psi. talked to people at TST and decided Iwasn't getting enough fuel to create much boost. I did a running fuel pressure test, at 55 it would run 26-28. It would then drop to 20 without any changes and back upto 26. the engine sounded the same when it dropped. I coul never get fuel pressure to 30. I put a new lift pump on thinking it might also cure my low rpm shake. Now I have 22 at idle and28 or so at 1800 and it does not flucuate but Isolved nothing NowI don't have hardly any boost under normal acceleration andthe most I will see is 15psi at best . I have smoke only when I open it up at low rpm. truck seems to run normal but it never had the power I thought it should have. Help me please. The more I spend the worse it gets.

 

[Dieselnerd]

Two things come to mind, they may not be your problem but are worth checking.

1. The pressure line going to the diaphram at the back of your injection pump. Is it kinked, broken or off? This is the boost signal from the turbo telling the pump it has enough pressure to give it fuel. Normally if this is a problem you have trouble on initial takeoff.

2. Leaks in your hoses from the turbo to the intercooler and from the intercooler to the intake manifold. Check for tightness.



I agree with TST, it sounds like you are not getting enough fuel. I'm sure you have already done the obvious like change the fuel filter. A clogged filter will also give you similar symptoms. Maybe the real Guru's will have more to say on this...

 

[Bhale]

Do you have a CAT on your truck? It might be getting clogged and that could restrict your exhaust flow and boost. Also, check to see if your wastegate is functoning as it might be stuck partly open. The max boost you'll see on a stock CTD is around 26 under load and 5-10 at highway speeds on a level surface. If you want more fuel, get a TST plate and an EGT gauge. How many miles are on the truck?

 

[jheath]

I've got a new filter (wix). the truck has 114k on it. I tried unplugging the hose to the wastegate and made no difference. however I did not plug the hose or the fitting would that make a difference? No cat. E. T. 's are around 600 to800 normal driving. I have checked and double checked clamps and hoses and cooler. I am tempted to figure out a way to pressure test the plumbing. Keep in mind though I have not set my timing since I had my pump off other than initial setting or the lever I should have looked at when I put my #8 plate in. I have been so busy trying to get my rear brakes to work all the time that I havent got back to my engine.