Hello,

I am new to posting, but do read quite a bit here. First of all, I have a 1988 Ford F-350 with the 7.3 diesel. It has had a hard start problem since I bought it 4 months ago. I thought it was a general problem. But through a process of elimination I have found that it is mostly on the front tank. The rear starts fine 95% of the time.

To start it on the front tank I have to try about 6 or 8 times and pump the accelerator pedal throughtout each attempt. This happens first thing in the morning or after it has been sitting for several hours. The rear tank I just push the accelerator down once and turn the key, it fires right up.

Repairs that have been done by me so far are:

1. New Glow Plugs
2. New Glow Plug Controller
3. New Fuel Lines Including Return Lines
4. New O-Rings
5. New Fuel Pre-Heater
6. New Fuel Pump
7. Fuel Additive at Every Fill Up

Anyone have any ideas as to what else to check? I have had it in the best shop around here and they can't seem to figure it out either.

Thank you all in advance,
Robert
Portland, OR

 

Does it run for a few seconds and then die, or just not fire up at all?

Did you replace the return line caps? If not, they may be distorted and may not be seating with the o-rings. Did you use small "worm drive" clamps on the return lines? The really small ones aren't very round and can be problematic (been there, done that). Even though fuel may not be leaking out, air can still leak in to the return lines. Air leaking in is what causes starting problems.

Diesels don't have an accellerator pump like a carburated gasser, so pumping the pedal doesn't pump more fuel in to help it start (I know, it's a hard habit to break, especially if you've ever owned a Cheby).

If it really only happens with the front tank, I'd suspect the lines between the selector valve and the rear tank. Does it happen more when the tank is low or the truck is facing down hill?

 

Thank you for your reply. It hits but probably only a second or two. THen it dies and is a killer to restart.

Caps were replaces - they used spring clamps - not worm drive.

Wow, that is useful information. So just cranking it not pumping the accelerator is what I should do? (Until it is fixed)

If I park facing downhill it is better. Still not great, but better. I am not sure about fuel level. I don't think it makes a difference, but I am not sure.

Thanks!

 

Be careful to crank on the starter for a maximum of 20 seconds and then wait at least two minutes before trying again. It sounds like you're almost there, it would be a shame to have to buy a new starter too.

To help get it started faster, push in the schrader valve by the fuel filter while someone else cranks it over until you get fuel coming out instead of air.

Start-then-die is a classic symptom of air intrusion. Again, since the fuel return system isn't under pressure and since air molecules are much smaller than fuel molecules, it is very common to have an air leak without any visible fuel leaking out.

It sounds like a problem with the lines between the selector (inside the frame rail below the drivers seat) and front tank or a problem with the pickup tube being broken or cracked inside the tank. Mine does the same thing, but only below 1/3 tank on the rear tank (pretty sure it's the pickup tube).

Others who have dealt with this problem should be along soon. Until then, check the fuel lines and connections very carefully. Loosen the clamps wherever the lines are attached to the frame and look carefully for pinholes or rust.

Good luck

 

If the rear tank is starting fine then you have either a rusting front fuel line or the in tank pump might be going bad. Both tanks go to a common place on the frame to a control valve.

 

Either the O ring in the suction line between the selector valve and the front tank sending unit is leaking, or you have a cracked pickup tube in the tank.

The tube cracked can show up at any fuel level below 1/2 tank.

Also there could be a rust hole in the fitting where the suction line attaches to the sending unit.

No in tank fuel pump on the diesel.

 

When I'm starting my truck it turns over & sounds like it is trying to start but can't quite get there, i punch the accelerator 1 time & bamm it starts. it works for me.

 

Yes, I know what you mean. Some of the old Metro buses in Seattle had Cummins motors in them. When they were shut off hot, I swear they'd crank over at about 30 rpm. When a cylindar came up on compression, if you punched it they'd fire right up.

However, I still believe that pumping the pedal a bunch of times before turning the key won't do anything...