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| Air In Fuel Filter http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=34775 |
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| Author: | Wobbly [ Tue Aug 05, 2008 11:07 pm ] |
| Post subject: | Air In Fuel Filter |
This may have already been discussed ad nauseum, but if not... |
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| Author: | msilbernagel [ Wed Aug 06, 2008 1:07 am ] |
| Post subject: | |
Never had this happen - I've had it run strangely (the no MIL limp mode, or missing/smoke) but no fail to start that I"m aware of. Mark |
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| Author: | gmctd [ Wed Aug 06, 2008 1:12 am ] |
| Post subject: | |
Prollem being, the engine is always higher than the fuel tank - maybe straight down the side of a cliff would reverse that positional relationship, but not many hills outside of MOAB will get the tank higher than the engine - major problem is the fuel manager head is always higher than any other point in the fuel supply system, tank to engine - air will always ascend and collect at the highest point in a system - one solution is to replace the slip'n'click plastic fittings at the tank with rubber hose and clamps - 'nuther solution (and my fav), of course, is add a lift pump - DCJ installed everything else for ya: kick the habit and do the deed |
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| Author: | ATXKJ [ Wed Aug 06, 2008 8:55 am ] |
| Post subject: | |
2 trips to Moab before I got the lift pump installed - and several hills I was sure I was going to fall off of (trust your spotters) - and no stalls - no engine issues at all on the trails. 1 glitch on the highway headed to Moab - probably due to bad fuel - dumped in lot's of Powerservice until I could change fuel filters. I still think the root of all air in fuel issues is the fuel head itself - it's very difficult to mold plastic around connectors so that they're airtight. The lift pump pressurizes it so it doesn't pull in air - a Racor gets rid of the plastic. If you have an air leak - the angle may make it worse - but the angle's not the problem. |
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| Author: | Wobbly [ Wed Aug 06, 2008 9:59 am ] |
| Post subject: | |
gmctd wrote: Prollem being, the engine is always higher than the fuel tank - maybe straight down the side of a cliff would reverse that positional relationship, but not many hills outside of MOAB will get the tank higher than the engine - major problem is the fuel manager head is always higher than any other point in the fuel supply system, tank to engine - air will always ascend and collect at the highest point in a system - one solution is to replace the slip'n'click plastic fittings at the tank with rubber hose and clamps - 'nuther solution (and my fav), of course, is add a lift pump - DCJ installed everything else for ya: kick the habit and do the deed
The question is poorly worded. All my non-starts were associated with parking uphill, and with being parked for several days or having a low fuel level in the tank. These observations seem to indicate that elevation difference between the injection pump and the level of fuel in the tank, along with parking time are factors in the non-starts. When the filter head pump had to be used to enable starting, either the engine had never fired, or had fired only for a second or two. This means that the problem is air in the IP low pressure side. If there's fuel remaining in the line from the filter head to the IP, the engine should start and run until air in the filter head is sucked into the IP. My guess is that fuel drains back from the IP to the tank under gravity while parking. If the filter head and fittings were air tight this fuel would not drain back to the tank. Having an elevation difference between the IP pump and the fuel tank would be a factor in how long it takes for enough air to enter the IP and line between the IP and the filter head to prevent starting. The IP does purge some air during engine starting. An alternative to adding a pump might be to loop the return line from the IP so that its high point was above the fuel filter head. This might prevent fuel from draining from the IP. Not very pretty, though. |
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| Author: | bugnout [ Wed Aug 06, 2008 10:24 am ] |
| Post subject: | |
Check the fuel heater plug. See if it shows signs of melting or overheating. Alot of problems with air invading the fuel head have been traced to this. |
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| Author: | gmctd [ Wed Aug 06, 2008 12:50 pm ] |
| Post subject: | |
Understood, nose up, nose down - I was just being multi-faceted, otherwise known as facetious - your fuel manager is definitely leaking, as the connections to and from the aluminum head are clamped rubber hoses - 1rst check is the heater, as suggested - pull the connector and look for charred appearance - could also be the primer pump - could be the fuel filter is loose, or the WIF element - tite enuff to not leak dense fuel, but not tite enuff to prevent air leaks - prolly time for a new fuel manager head, courtesy of DCJ - then the lift pump |
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