'95 Usually runs on diesel or veggie oil, now won't run at all

[donwally]

In the last week or two my truck has been harder to start. I'd crack a fuel line and some fuel would bleed and then it would start. Monday, I struggled to start it on diesel, switched to veggie oil, ran it for 2 hours perfectly and parked it. I came out 3 hours later and it wouldn't start on anything. I cracked the fuel line now, and no fuel. I replaced the fuel filter and fuel comes out of the bleeder valve at the top, but not out of the line. Is it automatically the injector pump again and if so, how can I tell? Any help would be great. Thanks.

 

[orrum]

Welcome Donwally! I am a newbie to diesel trucks but been running my Mercedes on a single tank unheated blend for a year. Been reading up on here to change my truck over to wvo. U need to check ur fuel supply. U have a filter sock in ur tank that may be stopped up. U also have a filter screen in ur LP that could be stopped up. U also have a last ditch filter screen in ur FFM that hopefully is still there that u need to clean when u change the fuel filter, b careful its easy to lose. Some folks dont even know theirs is missing. There are some really good mechanics on here that will help u. U need to fill out ur signature so they will know what u r working on. How long have u been on veggie, how are u filtering it? U need good clean veggie and u need prefilters before the LP and u need a extra filter to save the factory filter. Burning Oil, a member here named Leroy sells a excellant LP and prefilter setup and also a OPS mod that u need. How are u dealing with ur optic sensor seeing thru the wvo? R u sure ur LP is pumping? U need to put a gauge on it pre LP and check it out. Plus ur pmd needs to be relocated, Leroy can help u with that, he sells a cable to use to move it too. U cant get this stuff any better or cheaper.

 

[buddy]

Yes welcome. Need lots of details about the truck. What is stock, what is not, and as Orrum asked, need to know the nitty gritty about the WVO setup, since it sounds like you have a dual tank and dont mix, and do you typically flush it with diesel before shut down?

It could be any number of problems, simple one is a PMD if youre not familiar with it yet. And it would have nothing to do with the fueling system, just a failed electronics piece. Unless the PMD is still on the IP and you preheat the WVO to like 170F, so the IP is always hotter than normal.

 

[orrum]

Oops meant put pressure dauge pre IP. Hello Buddy, go fix him up my friend.

 

[orrum]

Buddy his truck will run 15-20 degrees cooler on straight veggie oil if that has anything to do with ur thermostat setup on ur writeup that I am sure he needs a copy of, its very good and a ton of help.

 

[donwally]

Not being a mechanic, here's what I know. The truck is stock. The WVO system is a separate system. Greasecar.com put it in for me. There is a black box connected to a heat sink in my front bumper. All of my fuses seem to be unblown but some are black blocks that I don't know how to test. I do flush the veggie oil system when I shut down, if I think the oil is going to cool below 120 before i'm gonna get back in the truck. I had to replace the injector pump last year. The mechanic said the car was famous for it. He said he put in a bosch pump and I have about 8k miles on that one. The truck has been generally hard to start this season. I had a transmission problem with it in December and got frustrated and put it away for winter. It turned out to be nothing. I was told that I didn't winterize my diesel properly and that was causing my starting issues. It struggled a bit, but always started. This week was the first 2 times, where it struggled to the point of running the batteries down without starting. With some effort I got it to start those two times. That was last Friday, and Monday AM. This last one, was Monday afternoon. I had the truck towed home, charged everthing and still can't get it running. It cranks strong and after changing the fuel filter, and bleeding it, and leaving it on the block heater all day so it registered close to 110 degrees, i'm not getting a single fire or a drop of fuel out of an open fuel line.

 

[ak diesel driver]

every 6.5er needs a spare pmd. I'd get one and try it

 

[donwally]

I'm assuming the PMD is the electronic in the bumper?

 

[Burning oil]

Could be glow plugs, but if you got block temp to 110 you would think it would fire if it was just GPs. Could also be the PMD do you have a spare to try?
I run a two tank WVO system also. Do you blend at all in the diesel tank? if yes I would remove the tank sock and install a LP spin on pre filter and you might want a new LP while your at it. Next blow out the lines, with LP removed blow back toward tank with fuel cap removed. Also remove the line to the stock filter (FFM) and blow air down to the LP outlet line with a hose over the line and directing discharge into a clean bucket.
I had all kinds of crap come out of mine.
What year is your truck? Got any pictures of the valveing on your WVO system?
www.pmdcable.com is my web site check it out it may get you thinking.

Edit: you guys type faster than me, yes PMD is the box on heat sink in the bumper. It has been relocated from its normal position on the IP

 

[buddy]

The IPs are famous for dying, and possibly even more so with veggie oil, but I would try a new black box (PMD in bumper) and try eliminating the cable and plug it in up by the IP where it was originally. So does the veggie system have filters, heaters, you switch a valve? A setup like that is not for the novice and most WVO guys know everything about their kits. And do you get WVO and filter it before using it, or how do you get the WVO?

At the end of the attached file are some no start diagnostics you can check. This engine has quite a few quirks, not real difficult, but will puzzle most mechanics and normal drivers. Not the set it and forget it, or just put fuel in it type of vehicle, especially with the WVO system. So the more you read and learn about it the better.

And orrum, those with separate WVO setups that run pure or very high percentage WVO they need fuel heaters because veggie has to over 150F to atomize even close to diesel fuel. So fuel going into the IP would be hotter and fuel, although heated in stock form, is partly a cooling agent for the IP.

These electronic IPs have Optical Sensors inside the fuel flow that needs to see through the fuel and veggie can cloud the lens, the first couple pages of the attached file cover how you can also attempt to remedy that type of situation. And also I would not trust the mechanic set the IP timing correctly, ask him what scanner they used to set the timing and what the TDCO value is. The attached file explains the IP timing quite a bit.

 

[donwally]

Thanks for the advice

Most of this is probably beyond my skill set but in reading the attachment, there were some tips in chasing the gas. I thought the FSOL fuse was one of the encased ones where I couldn't pick it up and test to see if it's not blown. If that's not accurate, please correct me. I'll also try the idea of loosening the inlet hose on the IP to see if fuel leaks. I know fuel goes into the fuel filter, but there is definitely none coming out by where the fuel line meets the engine. Assuming fuel goes into the filter, but doesn't come out of the line, what happens next?

 

[buddy]

As Orrum mentioned, the filter can be plugged or the "last ditch screen" inside the filter housing (called Fuel Filter Manager or FFM). This last ditch screen is located under the filter around the central shaft of the FFM, and often times the filter may pull it off when taking the filter out. Other times they are on there real good and over time in some instances get plugged up. So good to check the bottom of the FFM and this little screen around the middle of the central shaft. From there, it exits the FFM and goes to the IP inlet. So best place to check for fuel is the IP inlet. The drain hose on the thermostat crossover is actually pre-filter and would not catch filter or screen plugging issues. Also, if the return line gets clogged by cold veggie or the valve that must change return lines get gunked up you could have issues.

This vehicle and with a complicated WVO system is not for the faint of heart.

I am not familiar with the black boxes, but maybe someone with a 95 can chime in here. You need all the ECM fuses, FSOL and the larger fuses to be good. Best to check them with a meter, to verify there is straight continuity through them, because some can be deceivingly broken not visibly.

Everyone needs a spare PMD too.

 

[donwally]

Buddy,...

Thanks, that's the first thing that's given me hope today. So I should take the fuel filter out, and at the bottom, there's a screen, and I should check the screen for clogging. I was looking at the IP this morning. There is a hose that comes out diagonally. If I am standing at the bumper of the truck, and looking into the hood, the stem this hose attaches to is facing directly at me. Is that the IP inlet? It is in the center of the IP and is connected to a curved hose that runs in the general direction of the firewall.

 

[orrum]

U know when I switched my Mercedes to wvo it clogged a filter in a couple of weeks and then it was good for a while and then it clogged again and again and I put like 5 sets of prefilters and filters on in one week and it ended up not being a filter but a air leak and when I changed the filter it would run for a few miles and then act up and shut down with me usually on a bridge or traffic etc. Finally found the air leak and fixed that but I was going crazy changing filters! Might wanna check for air leaks, he has a bunch of fittings and valves and extra stuff for a two tank system and I think that increases the chance of a air leak.

 

[1995yukon65]

It's definitely sounding like a pmd issue, check and see if the mechanic hooked one up on the IP, if so that may be the whole issue, follow the wiring harness from the one in the bumper and see if it is plugged in on top of the engine.

 

[Burning oil]

The hose you refer to sounds like the return hose. The IP inlet is on the right side (as you look at it from the front) and is straight up (factory) it has a rubber hose with a 180* bend back under the intake.
An experiment you could try would be, take some clean diesel in a small fuel can (You might even use a cheap small inline filter for insurance) and with a temporarliy hooked up fuel pump and some hose attach it directly the the IP inlet. If it starts you will know IP and rest of engine is good.
You may have to crank it for awhile to prime up the fuel system.
BUT, again the fastest thing you can try is another PMD. I would do that first before anything else.

 

[Burning oil]

I was typing as 95yukon65 posted, but everyone is suggesting the PMD.
I think someone posted above to temp install the PMD back on the truck harness and eliminate the aftermarket extension harness (keep heat sink attached to PMD when you do it). What color wires are in your extension harness? If black= good chance of a inferior cable and would be suspect to failing.

 

[donwally]

Okay, so here's what i'm gonna do...

I get home around 6. The PMD, as I understand it, is the small black box on the heat sink. When my mechanic replaced the injector pump, he told me he replaced it with a bosch. As best as I can tell, there is still a black box (Stanadyne) on the side of the IP. There is a harness that comes out of there, but it's not easy to access. You're suggesting that I unplug the harness from there, and plug it into the box that I have which is in the bumper.

Additionally, I am to loosen the inlet hose which leads to the injector pump and crank the engine, to determine if fuel is passing through the fuel filter and into the inlet hose. Also, I need to pull the fuel filter which I installed yesterday, and look in the bottom of the fuel filter housing for some kind of a screen, to see if that is clogged.

All of that, I can do. I'll post what I learn as soon as I learn it. Thanks for all of the support out there. I do here you by the way, about the PMD, i'm just trying to avoid spending $250 on an untestable, unreturnable part, if that's not the problem.

PS Buddy, thanks for the encouragement. Don't confuse bravery with ignorance. I wish I did more research and chose an easier vehicle to try this with.

 

[buddy]

If the mechanic hooked up the one on the IP itself, you already have a spare PMD in the bumper. Figure out which one is plugged in and try the other.

If you first check for fuel at the IP, then you can eliminate the FFM as the issue. To power your Fuel Lift Pump (LP) without cranking the engine, you can just put the shifter in gear, and then act like your cranking by turning the key to crank/start. It wont crank the starter, but it will run the lift pump. That is unique to the 1995 model year. So you would need a helper to monitor the fuel and tighten it up while its pumping to make sure no air enters.

 

[Koots]

When my mechanic replaced the injector pump, he told me he replaced it with a bosch.

I don't understand this, did he mean Stanadyne? Because that's the company that makes our injection pumps.