Rebuilt Lehman 120 stuck @ WOT

[q240z]

Hi.
I had a set of Lehman 120s rebuilt back in 2008. They were test ran and performed flawlessly, but personal issues sidelined the installation. They sat inside the engine room of the boat on land until 2012, when I decided that newer and more powerful engines would be more appropriate. During the time the boat was fallow, I barred the engines over every couple of months. In September 2012, we pulled the Lehmans and just last week I took them back to the rebuilder for a check up before I list them for sale.

I just got a call from the mechanic saying Engine No. 1 started right up and ran fine, but when he applied throttle the engine went to 2650 -- the no load WOT RPM -- and stayed there. Moving the throttle lever back to idle had no effect nor did the shut down lever. They shut it down with a board over the intake to close off the air supply.

The mechanic noted that two bolts had been removed from the injection pump, which resulted in the oil draining out from the sump. He suspects thievery, since apparently sometimes these odd-threaded bolts strip out, and midnight auto supply in the marina gets the hard-to-find parts.

He swapped the bolts from Engine No. 2 into the pump on Engine No. 1 prior to restarting it and filled the sump with the proper amount of oil. He also turned the engine over with the starter until it developed oil pressure before feeding it any fuel. Oil pressure is 60psi and the engine runs great...it just won't come down off WOT.

I'm more familiar with Detroits, which have a very different fuel system and rack than these Lehmans. Any thoughts as to what might be wrong? Is there a secret place to bang on them with a hammer to get all the squirrels running right again?

Cheers,
Q

[phil23]

Had the same problem with a 90hp Lehman Dover and it turned out to be the rack holding open but I am sure they would have checked this.

[djmarchand]

It almost certainly is the rack stuck open after sitting unused for a while. That your mechanic hasn't figured this out is dissapointing. Should have checked it before starting the engine. It is a very common thing to happen.

David

[q240z]

Thanks for the responses. We figured the rack was having issues.

I cannot tell you how disappointing the mechanic has been...it's disheartening.

But back to the Lehmans...on a Detroit, you pull the valve cover to access the rack. I got the impression from the mechanic that accessing the rack on a Lehman required close to complete disassembly of the injector pump. Is it actually easier than that?

This is the earlier style Lehman with a separate oil sump for the injector pump.

Thanks again for any suggestions.

[gjordan]

Get the actual numbers off of the data plate on the injection pump and call a reliable fuel injection shop to find out how hard it is to access. I, like many shade tree mechanics tend to stay out of injection pumps, but I have freed up several old Caterpillar racks by simply taking off a side cover and tapping the rack back and forth with a small brass hammer. It worked on a few , and didnt work on some. I have no idea what the Lehman is like. Good Luck._____Grant.

[q240z]

Turns out the rack wasn't stuck, but two of the injector plungers were hung up. Apparently, the top end of the Minimek pump is splash lubricated. Barring over an engine in storage does nothing to keep the top end of the injector pump alive. Word has it the best long-term storage plan for these is to pull the pump off the engine and throw them into a bucket of diesel fuel.

Gotta love hindsight...