I have an International 6.9L in a bus and am experiencing the following problem. After travelling a few miles the engine loses all power and dies, by the time I pull off the road (10-15 seconds) it will restart and run normally for a few more miles then die again.
I have replaced the fuel filters, lift pump and check all the lines for potential air leaks.
Any thought or ideas that you can share to help me isolate the problem will be greatly appreciated. I'm supposed to be on my way to Talladega right now for the NASCAR races, instead I'm looking at a dead bus.
Thanks in advance and have a great day!!!
The Slims
What is the fuel level in the tank selected....... any abnormal noises from the engine. Did you have difficulty doing the lift pump R&R...... How tight did you make the fuel filter..... hand plus 1/2 turn with filter wrench is suggested.
What fuel pressure do you have cranking the engine in the starter.....
Do a pressure and flow test of the fuel pump at the Schrader valve on the filter header (FSS- fuel shutoff solenoid disconnected on IP). Remove the tire valve core and hook a hose and pressure guage on it should see 4-6 psi when starter cranking engine over. Then do a fuel quantity test same place, should see 1/3 pint in 10 seconds of starter engine cranking, route fuel to a suitable container with a hose. When all finished hook up the FSS wire .
Not sure if your bus has it but check for a water separator on the firewall.....these are a Ford known problem point.
The fuel level is a little over half a tank. It does get a little quieter prior to stalling. The lift pump install went well, I used a screwdriver to feel for proper cam position, confident it was correct. Fuel filter was tightened to spec. No water separator.
I will check the fuel pressure and volume at the location you mentioned (no Scrader valve, just screw in plug). I'll need to find a pressure gauge but that should be no problem.
Thanks for providing me with a starting point on this diagnosis!!!
Very good advice from PLC7.3. Especially look for that water seperator. It looks like a can with two fuel lines attached, a ring pull at the top and a drain hose at the bottom. If you have one it might be a good idea to bypass it with a short length of rigid pipe. It is also possible you have an intermittant problem with the injector pump fuel shut-off solenoid. Check the wiring connector there.
Since I'm focusing on fuel supply I wanted to point out a significant difference in my filter setup based on what I'm reading here and elsewhere. There are two filters in the system; a primary and secondary filter as illustrated in the photos.
Primary
Secondary
It's worth noting that there is no Schrader valve on either filter.
Is this considered a normal setup? Could this be contributing to my problem (although it worked fine when I first bought the bus)? This is a former Air Force bus so there could definitely be some "customization" going on under the hood.
It will idle all day long in the driveway but after being under power it will show the symptoms described earlier. Thanks again for taking the time to provide your input.
You can also check your fuel cap. When it stalls, get to the filler cap as fast as safely possible and pop it open, listen for a rush of air going into the tank.
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1986 F250HD Ex cab Fresh built up 6.9L diesel Lariat AC leather seats power everything w/full cluster, sterling rear 3.08LS gears, E4OD trans, ram intake ATS 088 turbo
1986 F150 Ex cab Lariat rollercam 5.0L on LPG AOD trans 3.55 gears 390 000Ks
I don`t like the idea of the lift pump having to lift the diesel thru a spin-on type filter. I would bypass that one and rely on the one on the pressure side of the lift pump. May be worth a try. Good idea from David85.
My best guess is your trying to pull/push fuel through too many filters....... I would advise only one filter with a spigot for draining water and it should be after the lift pump...... prior to the IP. Can you post a pic of the complete engine/filter(s) location.
If you can find a 7.3 filter setup complete top and base at a wreckers cheap ti can do the complete service....... filter and water drain. You can also just get the 6.9 filter header and put a filter with spigot on it.....
The image below represents the relative positions of the current filters. Fuel flows from the tank, to the primary filter, to the lift pump, to the secondary filter then to the IP.
With that said, and considering I don't have a fuel pressure gauge in hand, I'm gonna bypass the current Primary filter, take it for a spin and see what happens. If it stalls I will safely check the fuel cap for a vacuum in the tank. By the way, if I hear a hiss when opening the fuel cap what would that indicate?
Thank again, deiselmann's page is great, as is this forum. With resources like this who needs a mechanic!!!
I've bypassed the "primary" filter and bled the system of air. Lo and behold, it runs like a champ, better than it had in the past. Before it was pretty much WOT all the time. Now I've got a little throttle response and it runs awesome. My test drive took me 40 miles so I'm pretty confident I've found the culprit.
So...with the help of some great folks on FTE...I'm off to Talladega to enjoy a cold beverage and some stock car racing. Look for me on TV, I'll be here...
When I get back I'll look at my options for building a better filtration system. Thanks for all the help and have an excellent weekend!!!
Either a (vacuum) hiss or a pressure venting would indicate the plastic vehicles tank cap is not venting correctly........... but I do not think yours has that type of cap due to the fact it is that old...... 85 6.9.
'85 6.9L dies then runs fine for a few miles
Lariat AC leather seats power everything w/full cluster, sterling rear 3.08LS gears, E4OD trans, ram intake ATS 088 turbo
