| Author |
Message |
dave hartshorne (Yeeolde48)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, December 31, 2004 - 6:07 pm: | |
Hi All, I am new to the board, and have a 4501 we use to tow a 35 foot enclosed race trailer. I had the misfortune to breakdown twice last year due to what appeared to be fuel starvation. The first time within 3 miles of the track and the second time at the entrance to Bowling Green (blocked the main road for an hour. Both times the bus was in traffic on an uphill grade and lost power. As I tried to pull away the motor bogged and stalled and she would not restart without priming. I checked the fuel system for leaks etc, but did not find any. With the gear pump on the 8V71 pulling a slight vacume I understand how air could get in without a leak being obvious. My solution was to put a small electric pump in the fuel line up front by the tank that keeps a positive 2-3psi of pressure in the fuel line. The pump is rated at 80GPH free flowing and has been working well since July. We ran Cincinnati to Buffalo, NY with no problems. Recently I have had a few people tell me I should not run the pump as it will cause a drop in power and could lean the motor out. My thought is that as long as I keep any pressure in the line it has to be better than the gear pump doing all the work from the back? Anyone got any thoughts, I am not a diesel mechanic, and use this type of arrangement on my race car so it just seemed to make sense? |
TWO DOGS
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, December 31, 2004 - 8:09 pm: | |
It's just a lift pump....just supplys fuel to the injector pump....I did the same thing on a mack truck...the mack dealership wanted 175.00 for the lift pump...went to western auto...got a 30.00 elec. ---problem solved |
Geoff (Geoff)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, December 31, 2004 - 8:32 pm: | |
If you are sucking air into the fuel line adding an auxilliary fuel pump is not going to solve your problem (despite your recent lack of breakdown!). It sounds to me like your pickup tube in the fuel tank is bad or bent or something so that when you are on a incline it is not picking up fuel. Or were you you low on fuel each time you ran out?
--Geoff
'82 RTS CA |
dave hartshorne (Yeeolde48)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, December 31, 2004 - 8:49 pm: | |
Hi Geoff, I checked the pick-up after the first breakdown and found it had been brazed. It did not appear to be leaking but I replaced it anyway. Thought I had the problem solved, but then had the same thing again 2 weeks later. Tank had over 140 gal each time. I also did a leakdown on the line from the tank to the pump with no signs of any problems, and running the pressure pump I do not have any fuel spots to show a leak under pressure. Just scratching my head, but so far we have not broken down again, but I agree with you, I am not 100% confident I found the problem so not sure I fixed the root cause. I also found a lot of junk in the fuel, so put a second primary upstream of the electric pump and been changing it every 200 miles, cheeper than a full fuel clean. Could this be a cause, or could stalling the motor under laod have resulted in the same symtems of no fuel? or should I be looking for something else in the fuel system. I did replace the gear pump also.
Two Dogs, I paid about $100 for my pump, it was a spare for the race car and can run gas, alcohol or diesel, so decided to use it.
Thanks for the posts guys.
Dave
55 PD4501-304 |
Geoff (Geoff)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, December 31, 2004 - 9:11 pm: | |
You should keep in mind that testing the lines under pressure is not the same as testing them under suction-- often times sucking air into your fuel line will not show up when you pressurize the same line. But on the other hand you mention you have "junk" in the fuel-- if you are talking about algea in the fuel tank THAT could very well be your problem. Algea in clumps will plug up the pickup tube, once the suction pressure is off, the algea clump will drop off and the engine will run normal until it gets stopped up with algea again. If this is your problem maybe you have solved it by just running the engine with the auxillary fuel pump. Take the primary filter off your engine, cut it open and see if you find algea. Anyway, it doesn't hurt to add some algea treatment to your tank (IF this is the problem...)
--Geoff |
FAST FRED
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, January 01, 2005 - 5:47 am: | |
A simple addition to any fuel system is about $10 at the refrigeration store.
Called an armoured sight glass , it can be purchased with fittings that match your primary filter out line.
Installes in 5 min and you camn rotate the shield away to actually see the fuel coming out of the filter , on its way to the fuel pump.
IF you have any bubbles , (AIR LEAKS) you can actually see them.
Good toolbox item , or can be left in line.
Do it Your Way,
FAST FRED |
Bill Gerrie
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, January 01, 2005 - 8:00 pm: | |
FF
Excellent idea Fred. Even though I do not have a problem I think I will put the sight glass in the line just in case a problem should ever arise. Bill |
dave hartshorne (Yeeolde48)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, January 01, 2005 - 10:27 pm: | |
Thanks for the idea Fred, Will pick one up this week, will be a good reason to get the bus out of storage and run her before the weather turns cold again. I will install and leave in place, wil be a good reference.
Dave
55 PD4501-304 |
Donn Reeves
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, January 02, 2005 - 9:16 am: | |
It's possible that the gear pump is worn and won't maintain enough pressure at idle when the fuel is hot after a hard run.It might be worth putting a pressure gauge on it to see what it has.
Donn RTS NJ |
BrianMCI
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, January 02, 2005 - 10:50 am: | |
Y'know every so often Fred just blows me away with a really good idea. This is one of those rare occaisions. Great idea Fred!
Brian |
FAST FRED
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, January 03, 2005 - 6:38 am: | |
Check the archives , I have been pushing the idea for 5 years.
FAST FRED |
Prather
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, January 04, 2005 - 1:02 pm: | |
When I installed a new taller fuel tank in my Eagle 05 I had a similar problem, the 8V71 fuel pump wouldn't pull the fuel for some reason. I added a in line pump from NAPA,$80, in 1997 and everything has worked fine since. Since that addition I have put in a rebuilt engine but haven't checked to see of the new fuel pump can pull by itself. I also put a electric oil pressure sender at the discharge of the secondary filter and a 100 pound oil pressure gage at the dash, fuel pressure runs at about 85 pounds with new filters, and lets me know when it is time to change the fuel filters. |