‘94 Hard Start (video)

[Big T]

Update: I see my daughter in law posting snow play videos from our Big Bear Lake home, so I know he punted on working on the ‘94 Burb and is leaving it for me to work on.

 

[Will L.]

Update: I see my daughter in law posting snow play videos from our Big Bear Lake home, so I know he punted on working on the ‘94 Burb and is leaving it for me to work on.

So your son decided to go with his wife’s choice of happiness and deal with Dad punishment for it later. Yup- sounds like every man I ever met! Haha. Where is my son instead of being here to work on his dodge pickup to get it prepped for sale? At his girlfriend’s place. So it doesn’t matter wether it is to keep a rig or sale one- they always choose the gal over working on the truck, with or without the Dad.

 

[MrMarty51]

I think My youngest son moved to Alaska so He would not have to deal with Dad.
Oldest one lives here, He just ignores Me until He needs me for something.

 

[WarWagon]

Update: I see my daughter in law posting snow play videos from our Big Bear Lake home, so I know he punted on working on the ‘94 Burb and is leaving it for me to work on.

So this vehicle is not important to him. Clearly you have better things to do with your time and he can get it off your lawn.

 

[Big T]

I think My youngest son moved to Alaska so He would not have to deal with Dad.
Oldest one lives here, He just ignores Me until He needs me for something.

Same here. While I understand that time with the kids is important, transportation is also important. I suspect the need is less because his wife is a school teacher who is probably off for Xmas. But damn, all she does is play and post instagram videos and photos.

 

[Big T]

So this vehicle is not important to him. Clearly you have better things to do with your time and he can get it off your lawn.

It's out of my yard. It became important when he sold his wife's Subaru, then started using my Honda and broke the shift cable to reverse. Honda is repaired now and he's using it until I need it for work in a couple weeks. So he has a clock on his Suburban.

 

[Big T]

I’m leaving my ‘99 with the mechanic in our Stevensville, MT neighborhood to have transmission and transfer case replaced. So he won‘f be able to use that vehicle. Supposedly I have to go into work 2 days a week, and I’ll need the Honda for that. I will not ride the rail like I used to, not in this COVID environment. Can’t risk dragging home the Rona and exposing my wife.

I think we are down to a fuel leak between the lift pump and FFM. We should be able to easily correct that. Oh and I was the one who footed the bill for the Reman IP. The new Bilstein shocks arrive Xmas eve. Merry Xmas.

 

[Big T]

Colby replaced the fuel line from the Lift Pump to the FFM. Said he could not find the fuel leak. Truck was still stalling. So he mounted the PMD onto a heat sink using potting material and mounted it behind the bumper, replacing the other one. Same deal, still stalling. So he dropped it off at my place for me to go through it.

I fired it up and it ran good. Left it running to go in to clean carpet from old dog accidents. Came out after about 20 minutes and it was stumbling. Popped the hood and took some video of the clear return line while it stumbled, and there’s a burst of bubbles going through when it stumbles:

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There is also some fuel wetness around the base of the inlet fuel fitting to the IP:



So what do we have going on?

 

[Will L.]

The leak at the ip is just that- a leak. Remove, clean, inspect, re-install. But that is NOT your problem.

it is sucking air in before the lift pump- (most likely)

If there is a bad connection or hole in the fuel line after the lift pump, it will leak out fuel.
When there is bad connection or hole in the line before the lift pump- the lift pump is creating a vacuum in the line feeding it. So wherever a hole is, it will suck IN AIR. So you have a “leak” from tank to lift pump that is allowing air to “leak” in.

There is one other possibility: the ip is allowing air to get pulled in after the primary pump. This is REALLY rare. The way to verify is put clear line between the ffm and the ip. If No air bubbles are ever found going into the ip, but they are coming out- the only fix is resealing the ip or if the head/rotor is damaged and creating cavitation-which basically means having it rebuilt or replaced. This is very rare, but can happen.

Applying LOW pressure to the fuel tank- by using an air pressure regulator and making a fuel cap into an adapter to hook the air hose to- you can put in a couple pounds of air pressure, and hopefully it makes the fuel leak out wherever the bad connection or fuel line is. How poorly does this work? Poorly enough that this coming weekend -I won’t bother doing it with my nephew (hopefully we both are off work) and his 1988 k2500 6.5. We are just going to drop the tank, install new float assembly for the lines to be new, and run new fuel line to and from the engine.

 

[Will L.]

I have dreamed for decades of finding a clear fuel line that will withstand it all and use only it front to back. I have chased this probably 50 times in these rigs. It always sucks. The best answer on old trucks is simply replace the pickup assembly, all the fuel lines to and from engine. Then it is all good for 20 years if you use sae30r9. Cheaper line doesn’t last anywhere near as long.

Oh, and coat the assembly on top of the tank after install to protect it from rusting as fast.

 

[Big T]

The leak at the ip is just that- a leak. Remove, clean, inspect, re-install. But that is NOT your problem.

it is sucking air in before the lift pump- (most likely)

If there is a bad connection or hole in the fuel line after the lift pump, it will leak out fuel.
When there is bad connection or hole in the line before the lift pump- the lift pump is creating a vacuum in the line feeding it. So wherever a hole is, it will suck IN AIR. So you have a “leak” from tank to lift pump that is allowing air to “leak” in.

There is one other possibility: the ip is allowing air to get pulled in after the primary pump. This is REALLY rare. The way to verify is put clear line between the ffm and the ip. If No air bubbles are ever found going into the ip, but they are coming out- the only fix is resealing the ip or if the head/rotor is damaged and creating cavitation-which basically means having it rebuilt or replaced. This is very rare, but can happen.

Applying LOW pressure to the fuel tank- by using an air pressure regulator and making a fuel cap into an adapter to hook the air hose to- you can put in a couple pounds of air pressure, and hopefully it makes the fuel leak out wherever the bad connection or fuel line is. How poorly does this work? Poorly enough that this coming weekend -I won’t bother doing it with my nephew (hopefully we both are off work) and his 1988 k2500 6.5. We are just going to drop the tank, install new float assembly for the lines to be new, and run new fuel line to and from the engine.

Thanks, you’re confirming what I suspected:
Leak before the lift pump is the most likely place for it to suck in air.

 

[WarWagon]

The leak at the ip is just that- a leak. Remove, clean, inspect, re-install. But that is NOT your problem.

@Big T How old is the leaking hose? The hose from the FFM to the IP...

In general a leak on the LP pressure side wouldn't be a problem, but, kinking shut hoses and hose flappers gave me no end of dammed grief.

At the inlet of the IP so the pressure gauge was useless.

 

[Big T]

@Big T How old is the leaking hose? The hose from the FFM to the IP...

In general a leak on the LP pressure side wouldn't be a problem, but, kinking shut hoses and hose flappers gave me no end of dammed grief.

At the inlet of the IP so the pressure gauge was useless.

View attachment 69981

View attachment 69982

It’s from a FTB kit and is probably close to 10 years old. I will replace it. The hose from the tank to hard line is probably original, as is the hose from hard line to lift pump (Walbro FRC 10). I installed the spin on filter after the lift pump per instructions here.

 

[Big T]

Lowered the tank and removed the fuel lines. However, to the fuel tank the hoses have crimped on compression fittings that thread onto opposing nut on the pick-up/sender. The other end of the hose has a fitting compressed onto a hard fuel line that you cannot undo. The hard line has a compression joint further up the frame rail in front of the axle. I would have to order replacements for these and GM OEMs are in the $100 each price range.

How likely is it for a leak to be in these hoses? Should I first try replacing the hose from the hard line to the lift pump?

 

[Big T]

I’ve got some slight wetness on the fittings to the filter, but this is post lift pump. The hose from the hard line to the lift pump is brand new and is hose clamped on.

I guess I could ditch all this Walbro crap and go back to the stock in-line lift pump which has compression fittings to hard lines on both sides, thus less chance of leaks versus the Walbro with elbows threaded into the pump and hoses clamped onto the elbows.

 

[Will L.]

Anyplace it is wet, fix that.
I suggest eliminating the factory hose connector at tank- Those can leak sometimes as well.

What I do is remove the sending unit assembly from tank. Clean tank & remove sock while there. Buy regular flare fittings and cut- flare the lines. Then you can use a flare to barb fitting to hose. Haha

Best imo is cut off the metal end on the sender assembly. Double flare the end and put rubber sae30r9 hose on right there. Then put a prefilter on before the lift pump using normal barb fitting.

You can run metal line the entire way last connection at the ip. Doing solid all the way at the tank is just make the solid line attached to the tank and have a flare connector on both lines just infront of the tank.

Using a crappy lift pump because it has flare fittings isn’t a good answer. Use the good lift pump and make metal lines and flare the end is no biggie. Always use double flare. Buy the fittings to eliminate the hoses is not a bad idea.

I have done more than one truck with all rubber hose the entire way. Cut& flare the sending unit connections, threaded barb fitting at lift pump, filter and ip. Got decades from them that way.

It really doesn’t matter which you choose- just attention to detail when you do every connection.

 

[Big T]

Anyplace it is wet, fix that.
I suggest eliminating the factory hose connector at tank- Those can leak sometimes as well.

What I do is remove the sending unit assembly from tank. Clean tank & remove sock while there. Buy regular flare fittings and cut- flare the lines. Then you can use a flare to barb fitting to hose. Haha

Best imo is cut off the metal end on the sender assembly. Double flare the end and put rubber sae30r9 hose on right there. Then put a prefilter on before the lift pump using normal barb fitting.

You can run metal line the entire way last connection at the ip. Doing solid all the way at the tank is just make the solid line attached to the tank and have a flare connector on both lines just infront of the tank.

Using a crappy lift pump because it has flare fittings isn’t a good answer. Use the good lift pump and make metal lines and flare the end is no biggie. Always use double flare. Buy the fittings to eliminate the hoses is not a bad idea.

I have done more than one truck with all rubber hose the entire way. Cut& flare the sending unit connections, threaded barb fitting at lift pump, filter and ip. Got decades from them that way.

It really doesn’t matter which you choose- just attention to detail when you do every connection.

I don't have a flaring tool. The inline pump has the least risk for leaks. I'm going to delete the Walbro and filter install. I've got to get this back together TODAY as we leave for Montana next weekend. I need quick and immediate solutions, not some elaborate custom journey.

 

[Will L.]

Then buy the more expensive part is the option.

 

[Big T]

I got the tank back in and ran out of daylight to deal with the lift pump. Drove it over to Colby’s (1/2 mile) to pick up the shocks I got him for install during lunch breaks this week. I will also try and tackle lift pump change during a lunch hour. Truck had some initial stutters coming out of our place, but that cleared up.

 

[Big T]

Done further testing on this and I think we're down to a burnt out OPS. Lift pump only operates when the glow plug light is on. When you stop cranking the engine and there is still oil pressure, the pump is not operating. Every time it stalls, open up the FFM and it's empty. Get the FFM filled, and the engine lights right up and runs great, only to stall as the FFM drains again. New OPS ordered and on its way. Colby has the Leroy tool to install it.