Hailing all Apex gerus, help please??

[MRFUSION]

Okay so I spent all day at a buddies house trying to straiten out his 2006 Boondocker Apex problems. Here is the history, he bought it for cheap and didnt get any run time on it and found out there had been a fire at one time, meltied some wiring. He did a leak down on the engine and found some weak cylinders and removed engine and rebuilt with JE low comp pistons and head studs from Hurricane. Engine in and found apex doner with blown engine. He installed that wiring harness and i got him straitened out a couple of problems getting it to run now. So here is the problem,,, it starts up and runs great, go for one pull and okay but then gets worse, starts missing or dropping cylinders then will die and unable to start. Here is what I know, when it wont start it still has spark, testing #3 plug, has 32psi fuel pressure and zero codes, when it cools off it will start and idle for about 5 minutes then start dropping cylinders then will stall out unable to start. We have changed most things out including stator, ECU, Reg rectifier, fuel pressure regulator, TPS and most sensors, but I am looking for suggestions. Sorry so long winded, but any help would be great. Shad

 

[APEX 06]

Have you check psi on the motor when its warm.

 

[MRFUSION]

No did not do a comp test, we will do a leak down test tomorrow, had the head done by Dave at Hurricane and shimmed up. Only about 2 hours run time on new engine, this unit was acting like this before it was rebuilt too. Chasing ghosts from the previous owner I think.

 

[APEX 06]

You getting any codes

 

[kviper]

In tank fuel filter plugging? I have also heard of kill switch shorting.

 

[MRFUSION]

Kill switch checks out, okay tell me if this sounds weird, when it does start occasionally as long as you turn over the engine with the key it wont start but when you let the key go like your giving up it sometimes fires. Sounds crazy I know. Checked injector spray pattern too. No codes at all. I know the crank ID sensor wont let you start but no code 11 at all. Seem like it idles on 4 then slowly drops a cylinder each minute till it stalls out, then no start. Am running the MSD 2555 pump inline pulling from the tank with the RX1 filter, seems to have good fuel pressure when starting to fail too. Bypassed the new BD box too.

 

[APEX 06]

Have you checked the battary, these sled do odd things if that battary is low at all. Easy way to check is to hook it up to a car/truck and see if it works.


Sitting here in bed I I remember a sled that was sitting a SYI with the same isusse and found out it was the battary, after they had 20 hours of work I nm it.

 

[MRFUSION]

We think alike my friend, pulled up my truck and it fired right up, shut it down and thought all was okay but after it would spin over great but not fire, Here is another weird thing, after that I checked the battery voltage at the battery itself it was 12.5 but on my gauge on Diag it showed only 11.4 volts, a full volt lower, found no draws or grounding issues. Now go to sleep and dream me a fix. Shad

 

[HURRICANE]

Shad,you wrote that you had 32lbs fuel pressure.Was that a type O?32lbs is low.What fuel pressure do you have when it drops cylinders.To be honest,I had those symptoms once and the sled was running out of gas.
Dave

 

[MRFUSION]

We were using a liquid filled mechanical guage that he had and teed inline from the pump to the rail. I thought it should be around 42 PSI so we changed out the regulator (stock one) and still read 30 PSI, but I thought that was low too. When it starts failing the pressure seems to remain the same, when it wont start the pump cycles and sounds okay and is returning in the tank too. Can something go wrong in the rail somehow? I told him to change out his injectors and rail today. I am at a loss. I was going to call you today Dave.

 

[kinger]

Have you swapped out the idle air control valve? Its filled with a wax that as the coolant heats up the wax in there it lets the plunger give the engine more or less air. Sounds like if that is still original it may be defective from the fire and its not working properly once it gets warmed up.

Should have 42 psi that is what mine has and I have the same pump although mine is a in tank pump. Take that RX1 filter off and just run a open hose to see if it helps. Test this by just disconnecting the intake hose at the external fuel pump and putting another one and just stick the open end in the tank through the gas cap (then you wont have to open the tank, remove seat, etc)

Your getting close!