Reply
 
Thread Tools Display Modes
 
Old 09-09-2017, 04:03 PM   #1
Mini-Skoolie
 
Join Date: Jul 2017
Posts: 19
Fuel issue, need some help

So have been lurking a long time, finding lots of good information, and wish my first post was under better circumstances. I have a 1989 Thomas with a DD 8.2 that I bought before I knew to stay away from them. Engine runs great, started fine when I bought it, drove home fine, started fine for a few days until after sitting a few days it took longer to start, then started to really struggle to stay running, and now finally will not crank. I've isolated the problem to being fuel related. Did a ton of research and concluded I lost prime, or maybe the fuel pump went bad. I'm hoping to get some help from someone who knows more about how these, or all engines for that matter, work. My experience is limited to my little 2hp marine outboard, small engines, and little 90 cc motors i used to strap onto bikes.

So here's what I've tried. First I've looked at the tank access from inside the bus, pulled out the float valve and checked the line that goes into the tank that I believe is where the diesel is being sucked out of the tank from (correct me if I'm wrong) and it's clear, connections look good, didn't see any problems. Next I followed the fuel line to the fuel filter..again nothing out of place. Next I disconnected the fuel line from the other side of the fuel filter and used my hand primer from my outboard motor to pump diesel straight into the engine. When I do this the engine starts right up, runs fine, I'll see some foam sputtering from the fuel filter as the engine cycles, but when I reconnect the fuel line to the filter it will run for a minute and then sputter out so I know it's not pulling fuel past the filter. It's almost like the gas tank is no longer vented and the fuel isn't being sucked out anymore. Does anyone know where the vent line is coming out of the tank?

My questions:
How many fuel filters are there? I only see the one closest to the engine. Would they suddenly go bad after driving an hour? I don't know when the filter was installed so it could be that I suppose.

How can I rule out the fuel pump? I don't think this is what's wrong but I'm not sure.

I don't know how the bus could have suddenly lost prime after starting fine when I bought it and driving fine a few days after...the tank is more than half full so it didn't run low or anything.

Basically guys I'm out of my element here, and I've tried googling everything I can to find the solution, have tried a few things to no success, can someone offer some advice? I'd love to keep trying to fix this myself but I just don't know what else to try.

Also, doesn't help that there are no diesel mechanics within 100 miles that'll work on the bus...so I'm kinda on my own.

Thanks in advance
jlb8748 is offline   Reply With Quote
Old 09-09-2017, 05:39 PM   #2
Bus Nut
 
Join Date: Jun 2013
Location: Picton,Ont, Can.
Posts: 542
Year: 1997
Coachwork: Bluebird
Chassis: GMC
Engine: Cat 3116
Rated Cap: 72
Welcome I think you have come to the right place for advice, but it may not be mine. We all dread the no start condition so you might as well get used to understanding the problems that arise.

"and now finally will not crank. I've isolated the problem to being fuel related. Did a ton of research and concluded I lost prime, or maybe the fuel pump went bad."

Cranking is a completely different problem than fuel supply. So do you have two problems or one?
Further on in your post you say it does start after priming manually so I am confused at this point.
When describing a problem think it through and be very specific in your description.

You are on the right path checking things out. With the ignition on can you hear the fuel lift pump running? Get a new filter or two and replace if you just got the bus and that eliminates the filter issues.
Tighten everything you can see in regards to the fuel line fittings as they do have a tendency to back off after some time.

You need to fix this yourself to gain some confidence. No different than smaller engines, just bigger parts to sort out.

Good luck.

And please tell us details on the bus and engine.

John
__________________
Question everything!
BlackJohn is offline   Reply With Quote
Old 09-09-2017, 07:31 PM   #3
Bus Nut
 
Join Date: May 2016
Location: Georgia
Posts: 924
Year: 2001
Coachwork: Blue Bird
Chassis: IH
Engine: T444E
Rated Cap: 14
I suppose my first question is exactly how long has that bus been parked? Diesel fuel will grow microbes when sitting for an extended period, and these will inconveniently stop up your fuel filter. Fuel treatments are widely available to greatly help prevent this problem in the first place, but rarely done on a vehicle that is about to be parked for an indefinite period. So, it's quite possible your fuel filter is blocked. Some diesel engines just have one filter, some have two. I have seen a Ford bus that even had 3 (2 on the engine, one more underneath on the frame). On half a tank of old fuel, don't be surprised if it clogs another filter within a couple days. Buy 2 or 3 filters and keep one as a spare at all times. Fuel filters should be changed every oil change.

Once you've replaced the filter and primed it all back up again, if it's still not running as it should, then start checking the fuel pump(s). It's not common for these to fail so suddenly (but it can happen). Also a possibility is deteriorated rubber fuel lines allowing air to be sucked in, or a loose fuel line doing the same. "Foam" in a fuel filter is a possible sign of this.

As a rule, at least on these older diesel vehicles, there is no tank vent system like there is on cars. There may be a fuel return (not always) and the tank itself may have a vent (or the cap may be vented). To check this, open the cap and see if it relieves the vacuum (there shouldn't be any vacuum).
Brad_SwiftFur is offline   Reply With Quote
Old 09-09-2017, 08:45 PM   #4
Mini-Skoolie
 
Join Date: Jul 2017
Posts: 19
Quote:
Originally Posted by BlackJohn View Post
Welcome I think you have come to the right place for advice, but it may not be mine. We all dread the no start condition so you might as well get used to understanding the problems that arise.

"and now finally will not crank. I've isolated the problem to being fuel related. Did a ton of research and concluded I lost prime, or maybe the fuel pump went bad."

Cranking is a completely different problem than fuel supply. So do you have two problems or one?
Further on in your post you say it does start after priming manually so I am confused at this point.
When describing a problem think it through and be very specific in your description.

You are on the right path checking things out. With the ignition on can you hear the fuel lift pump running? Get a new filter or two and replace if you just got the bus and that eliminates the filter issues.
Tighten everything you can see in regards to the fuel line fittings as they do have a tendency to back off after some time.

You need to fix this yourself to gain some confidence. No different than smaller engines, just bigger parts to sort out.

Good luck.

And please tell us details on the bus and engine.

John
Sorry yes the engine cranks but does not start when the fuel line is hooked up, but cranks and starts fine when I manually pump fuel into the engine.

I've never changed a fuel filter before but have read it's easy. It's the screw on kind but when I've messed with it I could never figure out how to get the filter off.

Another lead I want to check is the vent line coming out of the tank. I don't know where this line is coming out of the tank so not sure where to check to see if it has somehow been clogged or limited somehow. It sounds like the bus dies in the same way my 2 hp dies when I don't have the vent cap unscrewed. Any ideas?
jlb8748 is offline   Reply With Quote
Old 09-09-2017, 09:57 PM   #5
Bus Nut
 
Join Date: May 2016
Location: Georgia
Posts: 924
Year: 2001
Coachwork: Blue Bird
Chassis: IH
Engine: T444E
Rated Cap: 14
The fuel tank may not have a vent "line" coming from it. It may just have a simple vent on the top. Not all tanks do. Some are vented through the fuel cap. Check it for vacuum first (this is fairly uncommon).

Some fuel filters are just like spin-on oil filters and are changed pretty much the same way. Many of us prefer filling them with fuel prior to installation, if possible. On some older diesel engines, they use the old "sock" type fuel filters. Usually these involve removing a lid, remove & replace, re-install the lid. The next kind has a housing which has a cartridge inside (the cartridge looks like the guts of a spin on filter). Some are metal housings and others are clear plastic. Basically you remove the top, replace the cartridge, and reassemble. On the plastic ones, they usually have a cap and you can pour a bit of fuel in once it's reassembled. Put the cap back on before starting the engine, otherwise it can suck air into the system. It's normal for these filters to have a low "level" with a fresh filter and when it reaches a full level, it indicates the filter is about clogged and due to be changed.
Brad_SwiftFur is offline   Reply With Quote
Old 09-09-2017, 10:02 PM   #6
Mini-Skoolie
 
Join Date: Oct 2014
Posts: 15
Yep, do what Brad_SwiftFur said. After changing ALL of your fuel filters, check and see if there was any water or other goo in them. If there is, you probably need to drain, clean and refill your fuel tank. If it won't start after changing filters and priming, get a clean 5 gal. bucket of fuel, get some Push-Lok fittings and fuel line. Disconnect the fuel inlet line on your fuel pump and connect the Push-Lok line there, put the other end in the bottom of the bucket of fuel and prime it. If it starts then, your problem is back to the tank. If not, most likely has a bad pump. (good luck getting one).

The fuel tank vent line is simply an open line the likely comes down the side of the tank. I have seen mud wasps build nests one the end of the line, plugging it. (That was fun to find). Good luck.
bigmackone is offline   Reply With Quote
Old 09-10-2017, 05:06 AM   #7
Bus Crazy
 
Join Date: Mar 2011
Location: Oregon/Philippines
Posts: 1,660
i dont think is vent line. however clearly problem is fuel feed system or something lke clog or pin hole in fuel line. diesel is quite simple to fix, just trace line, however, as mentioned before, change both primary n secondary filters and FILL them before u install them. is quite possible u r not getting fuel up to the primary if it runs but not start. also fuel pumps are quite easy to get, and one can use substitute as long as u choose right pressure n gpm.
fixing your fuel issue should be quite a simple fix
__________________
Jesus Christ... Conversion in progress.
chev49 is offline   Reply With Quote
Old 09-10-2017, 10:23 AM   #8
Almost There
 
Skipoffools's Avatar
 
Join Date: Mar 2016
Location: Southern Oregon
Posts: 71
Year: 1989
Coachwork: Carpenter (Cavalier)
Chassis: International Harvester
Engine: DTA360
Rated Cap: 63
If you have a shut off handle, meaning a handle you pull after turning off the key the make the engine stop, check to make sure it's pushed in all the way. This was happening to our bus.
Skipoffools is offline   Reply With Quote
Old 09-10-2017, 11:40 AM   #9
Bus Crazy
 
roach711's Avatar
 
Join Date: May 2010
Location: Farmington Hills, Mi (Detroit area)
Posts: 1,572
Year: 2000
Coachwork: Eldorado Aerotech 24'
Chassis: Ford E-450 Cutaway Bus
Engine: 7.3L Powerstroke
Rated Cap: 19
Ruling out a clogged vent is easy. Just remove the fuel cap and if it still fails it's not the vent that's giving you problems.
__________________
The Roach Motel
roach711 is offline   Reply With Quote
Old 09-10-2017, 12:43 PM   #10
Bus Nut
 
Jolly Roger's Avatar
 
Join Date: Feb 2015
Location: North carolina
Posts: 651
Year: 1986
Coachwork: Thomas
Chassis: Ford
Engine: Detroit 8.2
Rated Cap: 60 bodies
Add a fuel pressure. Guage or at least test ports on either side of the filter and after the pump.
My 8.2 was having intermittent problems with fuel and it ended up being a rubber fuel line was collapsing on the inside.
It took me installing pressure gauges to figure it out.
The ones on around the filter should be a vacuum or negative reading type cause the pump is sucking through not pressurizing out
Jolly Roger is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


» Virginia Campgrounds

Reviews provided by

Powered by vBadvanced CMPS v3.2.3

All times are GMT -5. The time now is 11:21 PM.


Powered by vBulletin® Version 3.8.8 Beta 4
Copyright ©2000 - 2017, vBulletin Solutions, Inc.