Mechanical 8-V Not getting fuel

[Joe Cannarozzi]

I have a copper tube coming from the tank out of "the tunnel" that goes through a manual shut off valve and then into the primary filter. If that copper line is 1 piece continuous all the way to the tank or if it has rubber sections in it at the tank I do not know.

I took that line off at the primary filter and blew air into it and bubbles could be heard in the tank. The fuel filter is new and full.

There is no water separator on this bus.

So from the primary filter to the fuel pump there is a rubber #8 Arequip line. I have pulled it. It is old and cracked and probably original and I am hoping is allowing the pump to suck air.

Recently I have been noticing having to turn over the engine way more than I used to have to to get it to fire. It has always started as soon as I hit the button. Now it will not fire at all. When I pulled the line coming OUT of the pump and turn it over it is not pumping fuel.

The only place I can see it could be sucking air is that one section of rubber hose before the pump and I will put a new piece on tomorrow.

If that turns out not to be the problem 2 questions.

The pump is attached to the end of the blower housing on a 3 bolt flange, is it just slid on a spline shaft or is it more complicated than that.

How much are they and can they be rebuilt?

The line coming out of the pump goes to the secondary filter and from their 2 lines go to the racks 1 for each side.

Dalej says their is a check ball in the secondary filter head that could go bad?

At least it happened here at home, I'm looking at that as a victory

[gmcbuffalo]

Joe
Try connecting a electrical fuel pump to the end of the rubber input line and see if you are drawing air.

GregM

[Joe Cannarozzi]

I suppose I could try that, I'd have to buy one though.

It has to be 1 of 3 things. First there could be a bad rubber union close to the tank that allows you to disconnect things to pull the tank level gauge and the likes. Second it is the rubber line I have pulled or it is the pump.

If I have to pull my holding tank to get at a deteriorated piece of rubber hose at the fuel tank I will finally get to install the sending unit in the tank I bought about 2 years ago and haven't installed yet

The pump is very small it is low pressure and looks easy to get out, I think. Wonder what one costs.

[Jon Wehrenberg]

Joe,

I can't even picture my 8V92 engine anymore, but some of thre things you mention may not be the problem.

My guess is anything between the primary filter and the tank is likely to not be admitting air. If it was, when the bus is at rest you would see a fuel leak since that line has fuel in it.

I have never seen the inside of a fuel pump, but usually they are fail safe. If they are driven they will pump because there are just positive displacement type pumps and do not have internal parts that wear. If you suspect the pump the cheapest way to deal with that is to go to a truck junkyard and get one. They will not pump air so you need to be sure the lines are full.

Have you considered a plugged system or water in the fuel? Diesel fuel will grow algae, and lack of use will allow condensation in the fuel especially if the tank is not full.

[dreamchasers]

Joe,

On the American Eagle I once owned (350 HP Cummins), the electric 'lift pump' developed a leak in a seal. When attempting to start the engine, air was sucked in the leaking seal causing hard starting issues and missing when running the engine at normal operating speeds. When I replaced the electric lift pump, all was well.

On the Eagle, the lift pump would run for a few minutes when the engine first started.

Is their an 'electric lift pump' for our Detroit engines?



Hector

[jimblu]

They come off easily depending on access, and have a small square drive that can strip. $100 rebuilt, $50 for a kit. They have an internal regulator to produce 65 psi, and a restricted fitting on the outlet back to the tank to provide a continuous fuel flow of a few gallons per minute.

You may have a lot of air or maybe the pump isn't turning. They can deal with a small leak. A Detroit will fire with the fuel in the injectors, so it may be dry and hard on the injectors to roll it a lot. You can often prime it by stuffing a hose in the fuel filler cap with a rag and blowing in it (1-2 psi max, lung power will do it), opening the line at the filter, and then the pump inlet. Fuel should flow out. It is a positive displacement gear pump.

[JIM CHALOUPKA]

Try to feed the pump from a make shift supply to segregate the problem.

JIM

[Jerry Winchester]

Joe,

I think you are on the right track with the lines. Typical problem is the fuel line just swells shut and no fuel comes from the tank. I have seen this happen repeatedly, especially on older trucks.

Second thing is, there is a check valve in the fuel line and if that thing is bad, the pump has to literally re-prime itself every time you stop for a longer period of time. I had that problem on my 8V coach and swapping out the check valve cured the "cranking for a while before it starts after sitting" issue.

You can buy these fuel pumps new on eBay all the time for cheap. I would buy a new or rebuilt on and not waste the time buying the kit to rebuild it. I'll bet we tossed a couple of them last time my dad cleaned out the shop.

[normancasson]

I had a post on 12-24-08 about a similar problem. It was kind of lengthly but you might want to refer to it. good luck.

[dalej]

Joe found the problem, it was the little air cylinder that retracts when you turn the key on. His wasn't. It is now. He's happy again.