Now fuel pressure
 

I have a 94 chevy 1500 with a 6.5td. I have rebuilt plenty of gas motor but I have never worked on a diesel before.
A little background on the truck.
The truck sat for over a year with no fuel, a rodent built a nest under intake and chewd up my injector wiring harness along with a few other none related problems I already resolved.
I fixed the wiring harness and cleaned out the nest. The problem I'm having is I have a steady flow of fuel at the injectors but no pressure. The same at my fuel filter. When I turn the truck over I get a little white smoke and truck tries to fire but wont. I have already checked all the electrical. Lift pump, fuel solenoid and pdm all working and I cant find any line blockage.
What else could it be?:argh:

If its been sitting and you are trying to get it running i can almost gaurantee it needs a new set of glow plugs. last 6.5 i got had 7 that were burnt up and open. white smoke is a sign of low heat causing incomplete combustion. If the glow plugs arent burning you will just make white smoke. Glow plugs are REQUIRED to get a 6.5 running at any temperature.

Thanks Josh, I will get a set and try them out.

they are cheap, and should kind of be changed every couple years anyways. If it doesnt get it running it is still good maintenance! But i think there are probably pretty good odds they are fried:c:

I found 3 glowplugs were bad and 1 fuseable link was bad. We will see if it works

great, does it run?

Not yet had to order fuseable link. I thought about bypassing it temporarily but decided just to wait.

probably a good idea. :tu: best to do stuff all the way the first time.

Whelp put glow plugs in went to crank and it just turned over didn't even try to fire. After looking over everything I found I need to re prime my fuel system. I just done it less than a weak ago but system full of air again . I got all the air out of the filter and at the solenoid but no fuel to the injectors. I get a little dribble at the number 2 injector that's it.:argh: Any one have an idea what could be causing air to get into my system. I don't want to re prime every time I let it sit a few days.

if its draining back to the tank there is a line, seal somewhere letting air back into the fuel lines and it is gravity bleeding back to the tank. If it isnt a big enough leak to let fuel out this can be very difficult to find. Any time i take the intake off one i change all of the fuel hose that is under there, its only a couple feet. The injection pump on these is pretty simple so lets walk through the system cause it sounds like you need to start over. fuel starts at the tank and is pulled out by the lift pump (any air leaks here will cause poor lift pump performance or air ingestion while running), leaves there under pressure (around 5 psi average) and heads up to the fuel filter (where the lines cross over to the trans is a common leakage point but probably not yours). Next stop is the fuel filter and our first chance to bleed air out (this module may have several o-rings and seals which could be a location of your leak it also has the water drain which you see up by the alternator and the bleeder on top.). If it was me i would have the lift pump on a switch i controlled at this point so i could keep the system pressurized at all times (not just when you have oil pressure which makes bleeding the system difficult and hard on starter and glow plugs). To assist in looking for leaks you could cover all the lines in baby powder, pressurize it, and look for the baby powder to change (Works -sometimes).

Our next stop is the injection pump, we have a internal transfer pump in here that can pull fuel from the tank in a leak free system and keep the engine running. It supplies the high pressure side with about 120 psi fuel transfer pressure. It is a vane style pump and very very very rarely experience failure but we have no way to check it. next its into the plunger bores and out down the lines to the injectors.

having read that novel i have questions.

Is your lift pump hot wired?
Does it pump fuel out of the top of the fuel filter housing?
Are we sure there arent any codes stored in the ecu?
Your glow plugs are all good now, but did you check for power in the circuit while its intact/under load?
Are you trying to bleed the injectors with your foot all the way to the floor on the accelerator?
Mechanical issues like timing chain failure/bearing failure have been assumed ok up til now, do you have reason to believe the engine is ok?
Is it turning over fast enough (i know, scientific), and can you hear compression?
When the key turns on can you hear and feel the fuel shut off solenoid activate? does it have power?

No I havnt hot wired the lift pump. Nor was I holding the petal to the floor while cranking ( I didn't know I needed to) As far as everything else it's good got power to plugs solenoid working I got 6.2 volts leaving Dom which is high according to specs but that could be my old meter. It has bad leads. As far as engine and timing I have no idea. I got the truck from a trusted family friend who said truck ran fine. Son hauled some trash ran out of fuel and just left it sit. I have a good fuel flow at filter and t valve after priming. I got good flow to shut off. But nothing after. Could the problem be in injector pump cause I had fuel to injectors last week but it wasn't 120 psi.

Also what's the best way to hot wire lift pump. I thought about taping into the harness and putting a 3 way toggle switch so I can change it back and forth at Will for future repairs. ( side note I'm planing on a full rebuild next year engine and fuel system.) so the switch would be handy to have but I can't find any elec diagram for how the relay is set up.

Welp I took your advice and held the petal to the floor and got fuel to my injectors. I cycled several times the hooked everything back up. Truck started :jump: then died 3 seconds latter:s: It wont even try to start now. So now I'm thinking maybe just air locked or return issue or both. What do you think?

sounds like air in the pump, go under the truck and tap into the pump on the hot wire and just run power to it from a switch or whatever is easiest. Holding the pedal to the floor increases fuel rate which speeds the bleeding process.

Also when you are bleeding a system once it starts it's always best to hold the rpm's up for a bit because it will still be processing air for a bit and it will die if left idling after it's initial fire. a minute or two is normally sufficient, sometimes this is required even after a fuel filter change.

Makes sence it died right after I let off the pedal.

:w2:

One thing after another. Went to re prime and noticed something smoking lick crazy on the right side between block and fram after a little investigating I found my ground strap going from block to firewall was hot as fire. I actually got a burn blister from touching it. So all things on hold New strap ordered will resume the fun tomorrow.:rock:

You need to finds out why you have current flow that is making the gnd that hot, is it electrical related or just ambient temp from proximity to "hot engine parts", just replacing it if there is a shorted electrical device will just burn out the new one.

There are multiple gnds on these vehicles it is possible one of the main gnds to hi current draw is bad causing trons to do their "normal thing" seek path of least resistance and passing too much current across that braided gnd.

BTW you don't need a special OEM style braided strap on back of the engine they use those for flexibility, heavy gauge automotive wire will do the same thing but because it is insulated you will want to route it away from hot engine parts to keep from melting/burning insulation.

One thing I also do is to add extra gnd between engine & frame get a 3-5' length of battery cable like you find on a card at auto part store with a ring lug at both ends, "polish to bright bare metal" a spot on the block or alternator bracket etc. and another on the frame, liberally apply dielectric or bulb grease to the bared metal spot and the lugs for best contact, with these PCM controlled engines clean gnds all of them are a must.

Since you are new to the 6.5 I HIGHLY RECOMMEND searching interweb for GM service manual or if you can't find one on line, subscribe for a year to alldatadiy.com then you can print off important stuff like schematics etc. and build your own manual, Chiltons/Haynes etc. give the generic info sort of ok but you really need GM specific info

^ all of that, normally start smoking grounds when the starter is going bad.

Yah started is on the list to replace. the solenoid doesn't always engage and the ground only smokes while trying to crank. I had already been through the truck cleaning grounds but I missed that 1. Lots of oil at motor attachment and corrosion at body attachment point. Thanks for the extra ground tip i'll do it