Skytrak issues 6036

[barklee]

Skytrak 6036: Guessing around 1999-2000 model year 12,000 hours
Perkins 4.236 engine turbo charged


Let me start from the beginning before stating the problem.

We were using our skytrak 6036 to move some stuff around the shop over the summer. I was driving it and all the sudden the machine just died. I thought it was out of fuel so i got out and checked it, turned out to be half full. From there i thought maybe there was a loose fuel connection or bad fuel line. After about 6 hours of inspection and replacing all of the fuel inlet and return lines we primed it up and tried it out. The machine would run for about 1 minute and die..... over and over again, each time it seemed to be sucking air as the bleeder had absolutely no pressure. I checked everything on the whole fuel system so i thought the lift pump had a bad diaphram so i replaced it to no result. After periodically messing with it over the last few months i got a mechanic involved. He looked it over and said he didnt think it was getting very good fuel pressure up to the injectors, and the pump needed rebuilt.
We had that done and put the pump back on. I havent messed with it and wasnt there at the time but the mechanic told me that it would run for about a minute and die...... Just like it did for me.
He went on to say that he was thinking that the timing had maybe jumped or that there was very little compression and the engine needs overhauled or maybe the cam was bad or damaged.

I am totally lost on these kind of issues but that doesnt really sound right to me. I was hoping to see if there were some easier ways to verify this and determine what the issue is? My mechanic is going in for some surgery and will be out for a while so im on my own for the time being. Thanks!

 

[Delmer]

My kind of mechanic, we both like to throw around guesses.

Bleeder having no pressure is shouting in your face. Fix that first. Does the lift pump have a primer lever? You can use that to tell if it's pumping etc. If there's no primer lever, I'd tee a pressure/vacuum gauge into the fuel line, either supply to the injection pump, or supply to the lift pump, and see what the pressure does when it dies.

Or you might want to overhaul the engine and see if that fixes the problem?

 

[barklee]

My kind of mechanic, we both like to throw around guesses.

Bleeder having no pressure is shouting in your face. Fix that first. Does the lift pump have a primer lever? You can use that to tell if it's pumping etc. If there's no primer lever, I'd tee a pressure/vacuum gauge into the fuel line, either supply to the injection pump, or supply to the lift pump, and see what the pressure does when it dies.

Or you might want to overhaul the engine and see if that fixes the problem?

Yes there is a bleeder and it appeared to be getting good pressure. It would shoot a full stream every time the pump was pressed down. I am fairly certain the fuel pressure is good because of the pump being rebuilt, i trust they did a good job. Ive taken things to them before and they do good work.

Yes, i definitely want to do whatever is the most expensive thing........... I was thinking of junking that motor and dropping in a Cat C-15!!!!:drinkup

 

[Delmer]

Assuming you have a priming lever on the pump, when it dies try pumping it and see if it's pulling a vacuum or pumping fluid or pumping air, that will tell you where to look next. Or use a gauge to confirm that the injection pump is getting pressure or not, and where to look next. Or keep looking for screens, elbows, banjo bolts, leaking filters etc.

 

[barklee]

Assuming you have a priming lever on the pump, when it dies try pumping it and see if it's pulling a vacuum or pumping fluid or pumping air, that will tell you where to look next. Or use a gauge to confirm that the injection pump is getting pressure or not, and where to look next. Or keep looking for screens, elbows, banjo bolts, leaking filters etc.

Sure seems like it is pumping a steady stream when you press down the primer lever. What i dont like is that on the primary filter, lift pump, and the sediment filter there is a brass compression fitting and a piece of copper tubing about 4-6" long on the outlet and inlet of each of these..... Seems like you cant get them extremely tight also there is no barb for the rubber hoses to grab on. Other than that i cannot see or find anything suspect. It wont stay running long enough to get any of the fittings to seep or show a leak if they are leaking. Thanks

 

[Moonlite]

Do you have banjo style fittings on fuel lines such as where the fuel line connects to the lift pump or where connects to filters? This is a bolt through an eye on the end of fuel line. Sometimes there are screens in these bolts.

 

[barklee]

Do you have banjo style fittings on fuel lines such as where the fuel line connects to the lift pump or where connects to filters? This is a bolt through an eye on the end of fuel line. Sometimes there are screens in these bolts.

Banjos on the primary fuel filter and the injection pump. No screen on the injection pump, i will have to check out the fittings on the primary filer.

 

[brianbulldozer]

Maybe check for restriction in the bottom of the tank from sediment. Pull the fuel line from the tank off at the lift pump, open the fuel tank cap, and blow a little air back into the tank. I would also be looking for a different mechanic. Jumped timing gear or low compression or bad cam doesn't exactly seem like a good diagnosis for an engine that starts and runs for a minute, then dies.

 

[barklee]

Maybe check for restriction in the bottom of the tank from sediment. Pull the fuel line from the tank off at the lift pump, open the fuel tank cap, and blow a little air back into the tank. I would also be looking for a different mechanic. Jumped timing gear or low compression or bad cam doesn't exactly seem like a good diagnosis for an engine that starts and runs for a minute, then dies.

Drained fuel tank, blew out every line on the machine. I don't exactly think he was correct either but thinking back we had a duetz break a timing belt and it acted the same way...... Do they make any kind of spray or machine that will detect a slight leak because like I said I can't see anything leaking.?

 

[Moonlite]

I had a cummins 3.9 had same problem replaced filter several times. Replaced filter housing and had pump rebuilt. Ended up had a bad batch of filters changed brand of filter. No more problem. Just a thought.

 

[barklee]

I was thinking about that also. I'm going to order a Perkins genuine filter for it and see what that does.

 

[barklee]

Fixed this today........ Certainly wasnt the timing or a blown engine. Since the mechanic put on the new injection pump i really havent had time to mess with this, so today i really looked everything over. The first thing i noticed was that there was marking paint on all of the bolts on the pump. The bleeder obviously didnt have that paint still on it from the guy trying to prime the pump. What i did notice was that there was still marking paint on the top bleeder (this Lucas pump has two bleeder screws). The top one was the main one we always used and it was stripped out before this happened so i tapped a bigger hole and used a cap screw as a replacement. I guess the injection shop never noticed this and just re-used my screw. My lovely mechanic must have never noticed this either even though i showed him this was how we bled the pump when this first happened. Anyway, it literally took me 10 minutes to bleed and i had it running.
In this end it must have been the pump because i bled that thing at least 20 times and it wouldnt stay running longer than about a minute. Thanks for all the help!