Engine/Transmission (1994 - 1998) Cannot prime fuel system after filter change

[ASHughes]

So,



After servicing my truck I backed it out of the garage to change the fuel filter. Naturally after doing a complete service including the transmission, I cross threaded the water in fuel sensor. It was late in the day on a holiday so I had to wait until today to buy a new sensor. I came home this evening installed the new sensor... ... and I can’t get the fuel system to prime. I've pushed the manual plunger until I thought I had broke my thumb, then I resulted to cranking the engine over until I thought the starter was going to catch on fire..... and not a drop of fuel in the filter. I've always used the manual pump to prime my fuel filters in the past with no issues. I can’t image the lift pump is bad, the truck was running when I shut it off. I've never left the filter off for that long (just over 24 hours) but I can’t see where that would create that big of an issue. Any Ideas?

 

[JR]

How were the threads in the housing where the WIF sensor goes into? Your sure the threads weren't damaged?

 

[GCroyle]

OK, Long shot, is the cam blocking you from getting the plunger to move, sitting on the high spot of the cam for pumping. If I'm right on this one, I'm buying myself a beer. Bump starter, try again. Did I say long shot?

 

[Texis]

I once watched a mechanic prime a system completely starting with a new, empty pump and filter housing, from the plunger. He used a 4ft long broom handle and stood next to the truck. It took him a LONG time (15-20 minutes of pumping) to get the system filled. Point is he wasn't in an awkward position and it took a LONG time!

 

[Joseph Donnelly]

Did you open a fitting (97s have a bleeder screw on the top of the fuel filter housing; iirc about the 95) to let the air out?

 

[fox]

I was told the plunger was a separate valve, but I had a 95 that was hard to prime one time, until I cranked it and then tried the plunger again and it worked this time.
Also I would suggest filling the filter with fuel or trans fluid before install. I recently bought a 98 and changed the filter, filled it and the plunger finished the prime.

 

[Joseph Donnelly]

Never use ATF in the fuel system. The friction modifiers will kill the injectors, etc. and it wasn't designed to burn well.

 

[ASHughes]

Well, I guess I'll go back to priming. I 've had the issue with the cam lobe being on a high spot and I bumped the engine over a couple of times to see if that was the issue. Then I tried priming the system by turning over the starter, to no avail. While using the manual primer, with the filter off, I get no fuel for several pumps and then I'll get a couple squirts of fuel, then back to nothing. It's almost as if I've lost prime between the tank and the lift pump? Does that make any sense to you guys?

 

[GAmes]

How long since you replaced the rubber fuel lines, including the 90* into the pump? A small crack won't leak fuel but will allow air to be sucked into the system. If you have a rust problem a good inspection of all the metal lines won't hurt either.

 

[MLee]

Barr it over a little, away from the high spot on the cam. Open the bleed nut on top of the fuel line above the filter and then prime it. Chances are that the primer botton needs rebuilt. If thats the case fill the filter for now.

 

[Cosmo]

A former co-worker of mine has run hundreds, if not thousands of gallons of ATF through his truck with no problems. He's not a diesel expert, but he was Mazda's tech of the year for a number of years, so he's not a total dolt.

Another major benefit of going with a FASS/Airdog lift pump is not having to deal with priming the system.

 

[GAmes]

I'd love to check out the carnage inside that engine:-laf Common sense would dictate to most people that ATF isn't a fuel substitute or an injector cleaner.

 

[ASHughes]

Still no luck. I've ordered a lift pump, fuel heater rebuild kit, and the 90* hose from the heater to the pump from Geno's. I'll give that try and see what happens. The only thing that really has me baffled is the fact that it was running perfect before I changed the filter, and now I can get any fuel out of the lift pump..... If the new pump doesn't do the trick, I guess my next step is to either drop the tank or pull the bed and replace all of the lines.

 

[GCroyle]

I haven't doen this on this series of truck, but MikeW told me about using this technique to prime our VW TDI's, don't see why you can't try it on the supply line if you can isolate it, but again, ain't tried it.

The line to the filter housing, can you remove and apply vacuum, like a Mighty Vac set up for brake bleeding. If you can't pull fuel wouldn't that be an air leak somewhere?

Good luck.

 

[Cosmo]

I'd love to check out the carnage inside that engine:-laf Common sense would dictate to most people that ATF isn't a fuel substitute or an injector cleaner.

But it does work just fine. As does used motor oil. Know what else common sense would dictate isn't a suitable fuel substitute? WVO. But it works too.

 

[mwilson]

I haven't doen this on this series of truck, but MikeW told me about using this technique to prime our VW TDI's, don't see why you can't try it on the supply line if you can isolate it, but again, ain't tried it.



The line to the filter housing, can you remove and apply vacuum, like a Mighty Vac set up for brake bleeding. If you can't pull fuel wouldn't that be an air leak somewhere?



Good luck.

On the TDI's you pull the fuel using a Mighty Vac hooked to the metal return line on the top of the injection pump. It would work on a Cummins if the return was not such a wretch to get to.



In the OP's case were it me I would do the following before spending a dime... .



Unhook the inbound fuel line where it quick connects to the steel line on the engine. Go get a 4-5' junk of 3/8" rubber fuel line. Clamp one end to that line and submerse the other end in a can or gallon jug full of clean fuel. If it primes after doing that then the issue is a fuel line or the fuel pick-tube has a pinhole rusted through it where it exits the sending unit. You need to pin this down before putting a bunch of parts on it IMHO.



I have seen Diesel engines that were behaving themselves do the very same thing after a fuel filter change. There can be a bad spot in the line somewhere that won't bother until the suction is broken either by changing a filter or running them out of fuel. Then the issue begins.



Keep us posted.





Mike.

 

[ASHughes]

On the TDI's you pull the fuel using a Mighty Vac hooked to the metal return line on the top of the injection pump. It would work on a Cummins if the return was not such a wretch to get to.



In the OP's case were it me I would do the following before spending a dime... .



Unhook the inbound fuel line where it quick connects to the steel line on the engine. Go get a 4-5' junk of 3/8" rubber fuel line. Clamp one end to that line and submerse the other end in a can or gallon jug full of clean fuel. If it primes after doing that then the issue is a fuel line or the fuel pick-tube has a pinhole rusted through it where it exits the sending unit. You need to pin this down before putting a bunch of parts on it IMHO.



I have seen Diesel engines that were behaving themselves do the very same thing after a fuel filter change. There can be a bad spot in the line somewhere that won't bother until the suction is broken either by changing a filter or running them out of fuel. Then the issue begins.



Keep us posted.





Mike.

Naturally, this dawned on me after I had ordered the parts out of frustration. I'm going to keep the parts coming and give this a try as soon as I get the time. My work schedule is a little crazy this week; it may be Sunday before I get to it.

 

[GCroyle]

Just strap a 5 gallon can to the hood, run the pickup line too it, nobody'll steal your truck with that setup.



MikeW I just put the vacuum on the filter discharge line on the VeeDub, got fuel, hooked and it ran and ran and ran... ... ..... until I crunched the oil pan in my driveway last weekend, got to answer the question, how much oil dry 1 gallon of oil takes to clean up. Fortunatly engine cold, at idle, immediate key shut off. Kicked butt vigorously, ordered new pan, even Dorman offers it. Next metal engine guard.



Hope the OP gets it figured out.



VW TDI rides low.

 

[ASHughes]

In preparation for the worst case scenario, I called my friendly Dodge dealer to get a price on the fuel lines just to know what I'm getting in to. They are discontinued..... good thing because they were over $400. I don't have tubing benders or flaring tools to make my own lines, would running rubber lines suffice?

 

[GAmes]

In preparation for the worst case scenario, I called my friendly Dodge dealer to get a price on the fuel lines just to know what I'm getting in to. They are discontinued..... good thing because they were over $400. I don't have tubing benders or flaring tools to make my own lines, would running rubber lines suffice?

You are getting ahead of yourself. Have you found holes in the metal lines? Marine grade diesel rated rubber fuel hose is available from LarryB http://www.fostertruck.com/catalogsearch/result/?q=fuel+line

Rather than trying suction to prime the filter I recommend you apply low air pressure to the fuel line out of the tank that goes to the pump. 10 or 15 psi will show up as bubbles wherever there is an air leak, if you have one.