HELP! Fuel problem

[Chris Buckner]

Another question guys, I’m in the process as we speak removing old lines and that bandaid electric inline pump. Once said and done when I’m ready to prime, shouldn’t I turn the key and hear a pump whirring noise or something to draw fuel into the lift pump to begin with? Or should I have to crank for it to turn on? I do not hear any whirring after a crank or with just key on

 

[DavidC]

On second gen 24 valves a quick crank will run the pump for about 30 secs. Probably have to crack a fitting up front to let the air escape until fuel shows up.

 

[DavidC]

I just reread this whole post. Are you saying the electric pump is gone and your back to the stock mechanical ?. If so there should be a primer button you have to manually operate on the pump. I'm sure other 12 valve guy's may have other idea's.

 

[Chris Buckner]

I just reread this whole post. Are you saying the electric pump is gone and your back to the stock mechanical ?. If so there should be a primer button you have to manually operate on the pump. I'm sure other 12 valve guy's may have other idea's.

Yes I removed the bandaid(electric inline pump) and now just have the mechanical lift pump(yes it has a primer pump on it) but isn’t there supposed to be some kind of electric prime when I turn the key to the on position?

 

[DavidC]

Yes I removed the bandaid(electric inline pump) and now just have the mechanical lift pump(yes it has a primer pump on it) but isn’t there supposed to be some kind of electric prime when I turn the key to the on position?

No electrical prime, only cranking the engine will work the pump, if the line to the pump from the tank is full of air cranking may be the best way out. I would crack a line at maybe the filter to let the air escape and refill the lines, or at the injection pump.

 

[JR]

Your best bet is to leave something loose, preferably at the highest point possible (between the lift pump and injection pump) and prime the system until you see solid fuel. Tighten back up and prime a few more times until resistance is felt and try to start. It.

If you already turned the engine over you will most likely have to bleed injectors also.

 

[BigPapa]

No electric fuel pump, no electric prime. Do not crank the engine trying to prime.

On top of the fuel filter head is a banjo bolt, I think it takes a 10mm wrench. Loosen it. Cut you off a broom handle @ 2’ long. Use the broom handle to operate the primer button on the fuel pump until you see fuel and tighten it up. It just needs to be snug, don’t torque it down hard. Now, continue to pump the primer button until you hear the over flow valve “squeak”. At that point you can start cranking the engine.

It may take MANY pumps, so don’t pump 10-15 times and quit.

 

[Timd32]

Now, continue to pump the primer button until you hear the over flow valve “squeak”.

Push Forest, Push......
I never did my fuel lines, but I prefilled my filter some, if the lift pump is on the cam lobe it could be hard to push, mine was fairly easy, and yep you will hear that squeak....its just in a tough spot at times.

 

[dieselshadow]

To prime a 12 valve, simply push the primer button on the mechanical fuel pump until it stiffens up and you hear the fuel squeak by the check valve. You’ll know when you got it. It still may be a bit cranky to start and rough at first, so don’t be afraid to give it some throttle as you crank it to keep it alive once it starts hitting.

 

[BigPapa]

To prime a 12 valve, simply push the primer button on the mechanical fuel pump until it stiffens up and you hear the fuel squeak by the check valve. You’ll know when you got it. It still may be a bit cranky to start and rough at first, so don’t be afraid to give it some throttle as you crank it to keep it alive once it starts hitting.

Hey, I have a shadow!

 

[MHalloran]

Crawl under truck & have a look at what supply & return fuel lines you can actually see. Part of the lengths that run to fuel tank will not be exposed because truck frame will hinder your view. If they look the least bit corroded I’d suggest getting LarryB’s hoses to replace all of it. I believe they are 2 different sizes if memory serves me. He sells supply & return hose by the foot. Replace it from engine to tank. Double clamp the ends. I did my 96 like this. You’ll never have to worry about it again.

 

[Iron Duke II]

Haven't removed mine yet. Will the fuel heater dash light remain on?

 

[Timd32]

Haven't removed mine yet. Will the fuel heater dash light remain on?

I did not know there was a light for it, so my guess is No won't stay on then.

 

[Iron Duke II]

One less thing. Thanks

 

[BigPapa]

There is no dash light for the fuel heater.

 

[Iron Duke II]

There is no dash light for the fuel heater.

Thanks

 

[BigPapa]

You’re probably thinking of the Water-In-Fuel light. That’s the sensor in the bottom of the fuel filter.

 

[Matt42]

There have been several topics in this one thread. I'm going to focus on the pinhole leaks that develop in the fuel return line on our Gen2 12 valve models, and how I fixed mine with some finality. There have been numerous articles over the years about finding the end of the steel fuel return line at the lower left side of the engine. With some light, while lying on my back, I was able to find it and then replace the hose that went from that point to the fuel tank. That worked for maybe 10 years. But the hard start caused by fuel drainback returned, and replacing the hose segment didn't cure it.

I decided to replace the entire fuel return line from the P-7100 injector pump all the way back to the fuel tank. That did the job.

The two most difficult parts are finding the return port on the P-7100 (which is actually easy, as you will see), and getting access to the return port on top of the fuel tank. You're on your own there. With some trucks, it's easy to get to the port between the frame and the bottom of the cab or bed. With others,the tank may need to be dropped a little bit. A fast fix that can work is to cut into the return line ahead of the tank, and hope that it isn't leaking nearer the tank. Here, the Technical Service Manual (TSM) is your friend. If you need to drop the tank, be sure the fuel level is low. I used a cheap transmission jack with plywood bolted to the top. But I was removing the tank to replace the fuel gauge sender.

The picture below was taken straight down and is intended to show part of the right hand side of the P-7100 injector pump. The left side of the picture is toward the front of the truck. I removed the original steel fuel line with the welded on banjo bolt, and then bent it out of the way. I installed a new barbed fitting that I bought from Geno's (more on that later) and connected it to a long diesel fuel hose. That hose runs all the way to the fuel tank with no cuts or splices. (I think I had to step it down from 3/8 inch diameter to 5/16 inch diameter close to the tank, though.) The new fitting should be obvious. It uses a hose clamp. The original steel fuel return line is bolted to he engine or head underneath something, and it's difficult to get to to remove. So I left it in place. My truck is subject to annual emissions testing, so I put a short bolt through the banjo fitting to indicate to the inspectors that it's been replaced. that has worked so far.

This image is from the Geno's online catalog. It shows the fitting I am using.

This is the URL to the fitting that I'm pretty sure that i ordered:
https://www.genosgarage.com/product/push-lock-banjo-connector-b1206/fuel-fittings-and-hoses
You'll need 17 mm (maybe a 14 mm) and 19 mm open end wrenches to install it. You'll confirm the sizes when you remove the old fitting. You'll use the same bolt with the new one. Two circular gaskets are needed. You can reuse the old ones if they are still good.

 

[BigPapa]

You can get you a banjo barb, but I just used the original tube. I removed the OFV and bend the tube back and forth until it breaks off at the mounting bracket. I then cut it with a tubing cutter a couple of inches past the bend from the OFV, flipped it over, slid the hose on the tube, and used two clamps on the hose. I did the same thing at the tube down at the frame. It’s been working fine for 400K miles.

 

[Matt42]

You can get you a banjo barb, but I just used the original tube. I removed the OFV and bend the tube back and forth until it breaks off at the mounting bracket. I then cut it with a tubing cutter a couple of inches past the bend from the OFV, flipped it over, slid the hose on the tube, and used two clamps on the hose. I did the same thing at the tube down at the frame. It’s been working fine for 400K miles.

Absolutely right,Scott! I didn't figure this out until after I had bought the fitting. (Insert duhhh sound here.) I make my own kind-of barb fittings using a double flaring tool, but without actually creating the finished double flare. It works for me with aluminum, copper, steel and thin wall stainless steel tubing.

1. Cut off the tubing length you want so that the end you're going to make into a home-made barb is clean and flat across.
   
2. Using an Imperial type double flare tool, place the end of the tube in the tool's retaining hole about 1/2 to 1 mm above the height specified by the tool's instructions and mandrel.
   
3. Insert the mandrel into the end of the tube.
   
4. Insert the flaring clamp's cone into the mandrel and the tool. A drop of oil on the end of the tube and top of the mandrel can be useful.
   
5. Slowly crank the clamp until the diameter at the end of the tube expands a little. Then STOP.
6. Remove the tube and check for burrs.

I learned this technique when I had my 1961 Rambler Ambassador 327 cubic inch V8 towed into a gas station in Arnold, California in 1970. The mechanic there showed me the bits of copper that had clogged the needle valve. Some damfool teenager had shortened the copper fuel line leading into the carburetor with a hacksaw. He cleaned out the fuel bowl, installed a cheap filter (the car had never had one) and showed me how to make the shop-made fitting, charging me $10. (I had $20 in ones and change in my pocket.) That was when the damfool teenager started collecting tools into his damfool adulthood.