Will start only with a squirt of starting fluid. Runs great once started.

[msgjd]

If the lines are blocked with crud, wouldn't I see HIGHER pressure at the tank? I'm only seeing ~2-3 PSI

This design of lift pump doesn't generate hardly any psi .. They are an "indirect" or "bypass" pump, for lack of a better term.. Most of the fuel gets slung aside as it spins.. When fuel level is low enough, you can hear it churn away from the impeller. If the fuel lines are restricted, this design of pump doesn't care .. No extra pressure is created.. The "excess" fuel the lines cannot take just stays in the tank as the impeller spins happily away.. Think of it as a little cooling fan on a desk or table.. Block the output of the fan with cardboard and the air just gets flung aside elsewhere.. No rise in pressure, the flow takes the path of least resistance

 

[biscuitwhistler37]

If the truck runs and drives normally after starting, fuel delivery is not the issue. Some trucks were designed to start with the accelerator pedal pressed, depending on the layout of the dashboard (source is the tm from 1981, starting procedure shows two methods, depending on layout). I'm wondering what your valves and the top of your pistons look like too, a stuck valve, misaligned rocker, or the piston tops themselves could be all gummed up with that nastiness. I've read too that a leaky head gasket can cause hard starting in these, which is doubtful in your case but not impossible. Beyond that, gasoline and a match.....

 

[Floridianson]

I forget what post it was but I was asking you to remove the return line that comes off the head and goes up to the T on the secondary. If I remember I told you to remove that line at the T and stick that line in a gallon jug or a jug and turn on the in tank pump. Here I was wanting to see if you're getting fuel flow through the head. A good running truck has a good fuel flow through the head and whatever pressure the intake pump is putting out. Without pulling out the TM between 4-7 psi was within spec. What we're looking for is enough fuel flow and some pressure to refill the pressure chamber every time the plunger goes down.

 

[7Dust]

I have decided to load the parts cannon again.

Im throwing another NOS injection pump at it.

its stupid expensive but this has gone on too long.

I just clicked Buy It Now. Should have it in a week or so.

sigh

 

[7Dust]

This design of lift pump doesn't generate hardly any psi .. They are an "indirect" or "bypass" pump, for lack of a better term.. Most of the fuel gets slung aside as it spins.. When fuel level is low enough, you can hear it churn away from the impeller. If the fuel lines are restricted, this design of pump doesn't care .. No extra pressure is created.. The "excess" fuel the lines cannot take just stays in the tank as the impeller spins happily away.. Think of it as a little cooling fan on a desk or table.. Block the output of the fan with cardboard and the air just gets flung aside elsewhere.. No rise in pressure, the flow takes the path of least resistance

Yeah - I get it.

Its just that I am supposed to see ~5 PSI at the tank?
I see 2PSI- ish.
I am getting good flow back from the HH into the tank but low pressure.

I am supposed to see ~5 PSI at the secondary filter?
It doesn't even register on the gauge.
If I open the bleed on the canister, fuel squirts up a few inches, but gauge doesn't regieter any real pressure.

 

[msgjd]

Yeah - I get it.

Its just that I am supposed to see ~5 PSI at the tank?
I see 2PSI- ish.
I am getting good flow back from the HH into the tank but low pressure.

I am supposed to see ~5 PSI at the secondary filter?
It doesn't even register on the gauge.
If I open the bleed on the canister, fuel squirts up a few inches, but gauge doesn't regieter any real pressure.

Any flow on a multifuel is a good flow when you turn on the accessory switch... Most of mine don't squirt up more than an inch or two at the filter bleeders, yet the trucks start/run normal.. The lift pump isn't designed to make pressure, it's only to provide constant flow.. I presume so that the HH doesn't lose prime should there be an air leak upstream of it, and it provides fast priming of the system in a tactical situation should you run out of fuel or have to change filters "field-expediently" ... That last term is something my last army unit constantly drilled into us..

If you are getting a noticeable difference in flow out of the HH return fitting or at the tank return fitting with the accessory switch on/off, the lift pump is doing its job and problem is not the lift pump itself.. I bet most of mine are only at 2psi if that , maybe 5 but surely is miniscule.. Never tested them .. The trucks will start with an inop lift pump as long as they haven't sat weeks on end and thus lost a certain amount of fuel back into the tank... I don't feel your problem is the lift pump .. Wish I had more for you ..

If the truck runs fine after you manage to get it started, it's not the plunger "button" in the HH .. A, just throwing that out there for anyone reading this who hasn't experienced it yet .. A dislocated button results in there being no high-pressure fuel to the injectors .. Basically, it's a spacer that sort of acts like a valve lifter for the hi-pressure fuel plunger.. Also, if the timing mark inside the HH is a tooth or two off,, it could logically make for a hard start, but I have not had one yet that acted like yours

 

[7Dust]

Fail. Parts Cannon Fail. Everything Still Fail.

I want to start another thread because this one is embarassing in the amount of fail.

Truck started fine before sitting up and I removed tank to clean and change the filters.
After that, truck would (hard) start with starting fluid only, then run great!

Here is what I have changed so far:
1. Cleaned Tank.
2. NEW (NOS) Fuel pulp and hanger assembly.
3. Rebuilt hard line from fuel tank to primary filter.
4. NEW Primary filter and O-Ring x 2 (I did it twice just to check)
5. NEW Soft Fuel line from hard line under radiator to Booster Pump (line under radiator is fine)
6. NEW (NOS) Injection Pump! (Booster pump, main pump, hydraulic head - all new!)
7. NEW NOS Secondary Filter Assembly The whole thing! Including pressure regulator, filters, o-rings.
8. NEW Injector Hard Lines. All six.
9. One New Injector to test injectors. It appears They do not pop when cranking. Only with starting fluid.
10. NEW Batteries 875 CCA each. Full charge. Cranks fine.
10. Probably more stuff. I spared no expense and have foolishly have thrown THOUSANDS of dollars on new parts at it withjout care just so it would start on its own without spraying it. I just want my truck back.

NOW - still will not start without starting fluid.
Its a little smokier.] than with the previous pump (which I also bought as NOS before parking the truck)

Still ~3PSI fuel pressure at the tank. No pressure showing at the secondary filter housing (but have flow of fuel).
No real pressure showing while cranking (even with new booster pump) but once it fires off, I get normal pressure.

I do not think this is an engine comprerssion problem since the injectors do not pop until I spray the truck, then it fires.

Maybe air? I don't know but there are no leaks. Ive had the primary filter out 3 times but maybe another won't hurt. I dunno.

Something happended after cleaning the tank and filters. I cannot find any place where crud could have gotten loose (that I haven't replaced) or air is intruding.

 

[Elk1111]

Eliminate the variables. Run a fuel line directly to the injection pump from a fuel canister.

 

[7Dust]

Eliminate the variables. Run a fuel line directly to the injection pump from a fuel canister.

Maybe - but not sure of a good place to introduce a fuel canister.

 

[jeffhuey1n]

Fail. Parts Cannon Fail. Everything Still Fail.

I want to start another thread because this one is embarassing in the amount of fail.

Truck started fine before sitting up and I removed tank to clean and change the filters.
After that, truck would (hard) start with starting fluid only, then run great!

Here is what I have changed so far:
1. Cleaned Tank.
2. NEW (NOS) Fuel pulp and hanger assembly.
3. Rebuilt hard line from fuel tank to primary filter.
4. NEW Primary filter and O-Ring x 2 (I did it twice just to check)
5. NEW Soft Fuel line from hard line under radiator to Booster Pump (line under radiator is fine)
6. NEW (NOS) Injection Pump! (Booster pump, main pump, hydraulic head - all new!)
7. NEW NOS Secondary Filter Assembly The whole thing! Including pressure regulator, filters, o-rings.
8. NEW Injector Hard Lines. All six.
9. One New Injector to test injectors. It appears They do not pop when cranking. Only with starting fluid.
10. NEW Batteries 875 CCA each. Full charge. Cranks fine.
10. Probably more stuff. I spared no expense and have foolishly have thrown THOUSANDS of dollars on new parts at it withjout care just so it would start on its own without spraying it. I just want my truck back.

NOW - still will not start without starting fluid.
Its a little smokier.] than with the previous pump (which I also bought as NOS before parking the truck)

Still ~3PSI fuel pressure at the tank. No pressure showing at the secondary filter housing (but have flow of fuel).
No real pressure showing while cranking (even with new booster pump) but once it fires off, I get normal pressure.

I do not think this is an engine comprerssion problem since the injectors do not pop until I spray the truck, then it fires.

Maybe air? I don't know but there are no leaks. Ive had the primary filter out 3 times but maybe another won't hurt. I dunno.

Something happended after cleaning the tank and filters. I cannot find any place where crud could have gotten loose (that I haven't replaced) or air is intruding.

When you pulled the cover to access the fuel pump, what was the condition of the gasket? Also, since we’re on the subject, the access cover, what kind of shape is it in? Last and probably least, have you checked the fuse on the top of the access panel? For what it’s worth, if the pump ain’t pumping properly, the electrical system is a remote chance.
Sorry if you already covered this previously. I only stop by to check on things. I’d love to see what actually fixes it.

 

[7Dust]

When you pulled the cover to access the fuel pump, what was the condition of the gasket? Also, since we’re on the subject, the access cover, what kind of shape is it in? Last and probably least, have you checked the fuse on the top of the access panel? For what it’s worth, if the pump ain’t pumping properly, the electrical system is a remote chance.
Sorry if you already covered this previously. I only stop by to check on things. I’d love to see what actually fixes it.

The old gasket was reusable and the old pump was probably OK after tank cleaning. The fuse was OK.

HOWEVER, I have replaced the whole assembly - hanger and pump are NOS unit. I also used a NEW gasket and new stainless screws.

The new unit has its own fuse so I have't checked it. Its still safety wired in.

 

[Elk1111]

Just run a fuel line to the inlet on the bottom of the injection pump. I used a boat fuel line with a pump. It at least eliminates a large portion of the fuel system and help narrow it down a bit. When mine didn’t start it ended up being the bowtie shaped piece in the hydraulic head. It was wallowed out and my injection timing was off.

 

[7Dust]

Just run a fuel line to the inlet on the bottom of the injection pump. I used a boat fuel line with a pump. It at least eliminates a large portion of the fuel system and help narrow it down a bit. When mine didn’t start it ended up being the bowtie shaped piece in the hydraulic head. It was wallowed out and my injection timing was off.

Ok - maybe undo the rubber line that connects the hard line under the radiator to the booster?

Without pressure / flow ? Just hope it sucks it up?

 

[jeffhuey1n]

The old gasket was reusable and the old pump was probably OK after tank cleaning. The fuse was OK.

HOWEVER, I have replaced the whole assembly - hanger and pump are NOS unit. I also used a NEW gasket and new stainless screws.

The new unit has its own fuse so I have't checked it. Its still safety wired in.

Just for giggles and snips, check the fuse. I’ve see many times a part that is new has to be fully inspected. I worked helicopters for 25 years. Never give Murphy a chance to bite you in the tookus.

 

[biscuitwhistler37]

Ok - maybe undo the rubber line that connects the hard line under the radiator to the booster?

Without pressure / flow ? Just hope it sucks it up?

It should without fail, the ip has enough suck to start and run the truck without a pump. I have done this many times in marine applications, fuel line directly to carb/ip on one end, a nice 5gal can of fuel on the other. I see no reason this would be different, just make sure you use a big enough fuel line. Don't be embarrassed/ashamed, we all go through this, and sadly, when we do find the actual problem, 9 times out of 10 we've looked at it a thousand times and never noticed. Forward, that's the key.

 

[7Dust]

Zero base pressure at secondary where I should see 5 PSI. There is 1psi showing at tank.

Zero psi at secondary when cranking.

1. NEW (NOS) pump and hanger
2. Cleaned hardline from tank to primary filter housing today (again)
3. Removed and checked, cleaned primary filter housing today (again)
4. New WIX primary filter (3rd one for no reason)
5. Removed and cleaned hardline under radiator (first time. Some varnish but no real obstruction)
6. NEW rubber line to IP Booster.
7. NEW (NOS) injection pump and injector hard lines.
8. NEW (NOS) secondary and final filter housing and filters.


WHY can I not get a base pressure?

it must be bypassing to tank somehow.

The bypass on the secondary filter housing AND on the Hydraulic head are both clean and new. The old units functioned the same way.

IF I pull the gauge off the secondary housing, fuel gushes out!

Why no pressure?

I can hear some fuel escaping back to the tank but how can it get there without going through the spring loaded bypasses at the filter housing and hydraulic head?

IF fuel is going through the bypasses, why can I not get a base pressure?

if I give the truck starting fluid, it will hard start,slowly build to 50 PSI.

if I kill the truck, I have to use fluid to get it to go again.

I will PAY MORE, I will do ANYTHING at this point.

Im out of useless ideas again.

 

[7Dust]

Video of zero base fuel pressure.

No presure while cranking.

The rattling is just 6 months of tools sitting on the fender.

 

[7Dust]

Just run a fuel line to the inlet on the bottom of the injection pump. I used a boat fuel line with a pump. It at least eliminates a large portion of the fuel system and help narrow it down a bit. When mine didn’t start it ended up being the bowtie shaped piece in the hydraulic head. It was wallowed out and my injection timing was off.

Just for giggles and snips, check the fuse. I’ve see many times a part that is new has to be fully inspected. I worked helicopters for 25 years. Never give Murphy a chance to bite you in the tookus.

Done. 24 volts at the pump. Still 1 psi at pump.

 

[7Dust]

It should without fail, the ip has enough suck to start and run the truck without a pump. I have done this many times in marine applications, fuel line directly to carb/ip on one end, a nice 5gal can of fuel on the other. I see no reason this would be different, just make sure you use a big enough fuel line. Don't be embarrassed/ashamed, we all go through this, and sadly, when we do find the actual problem, 9 times out of 10 we've looked at it a thousand times and never noticed. Forward, that's the key.

Done. No difference.
I also removed, verified clean or replaced with new parts all the way from tank to IP.
Zero base pressure. No pressure while cranking.

 

[7Dust]

Facts:

1. I am getting lots of flow all the way through all NEW parts all the way to the (NEW) hydraulic head.
Its not a lot of pressure, but the flow will fill a pint bottle in seconds.

2. The hydraulic head is firing. I can remove the line and see a strong squirt at each injector inlet.

3. The injectors are not popping properly.


I guess I'm going to mess with the injectors again.