1991 40' Executive 6V92 Detroit pusher has no power

[Mikedriggers]

Originally Posted by twinboat

If the injector rack is stuck, you shouldn't get any throttle response at all. Does it rev up in neutral ?

Did you see if the turbo spins. Pull the air intake off and spin it by hand. Should spin freely, like it's not hooked to anything.

The fuel pump is a gear pump, driven off the blower ( super charger ). I don't remember for sure but it may have an intake screen, to protect from debris tearing it up. Worth a look.

Last, is some of DDs have doors that closes, just above the blower. It is to shut the air down if the rack jams. Look for a lever and little latch that holds it open. It could be frozen and partially closed.

It's been a long time since I'v repaired or rebuilt the 2 stroke Detroit's.

Twinboat, It does have good throttle response in neutral just not enough power to un track itself. I will check the other things you mention I'm the morning. It cranks and sounds too good to be something bad..I'm thinking it's a simple easy fix...at least hoping it is

[stumpnc]

Mike I forgot about the airbox valves If one or both are stuck open you won't get enough blower pressure to make any power.

#4
Old 05-30-2014
Don Meyer Don Meyer is offline
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Join Date: Jan 2009
Location: USA
Posts: 1,028
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Hello James,

I've had my 8V92 for 12 years now and here is what I've learned.

Unless there is an internal problem, the air box itself should not cause you concern. I have pulled the covers off mine just our of curiosity, nothing to do or maintain in there.

Now your "slober tubes" are a different matter. They have a check valve located at the top of them. Just alonside the block. These check valves are designed to work in this fashion: At idle, the valves are open. this allows excess pressure at idle to escape. When you start to power up, the air pressure closes the valves to maintain full air pressure in the box. There are 2 different valves. One closes at about 900 RPM, the other at about 1200 RPM. I have the 900 units on mine.

The valves can become gummed up and will end up not closing all the way when you power up. So each year, when I'm doing my major maintenance routine, I pull the valves off and clean the thoroughly with brake parts cleaner. This should be a regular routine for any two stroke DD.

I also built a "catch can" that the tubes run into. This eliminated the traditional oil spot under the coach when parked. The can has two vents on the top and a petcock drain on the bottom. I drain this at each oil change. Usually only a few drops come out.

Hope this was helpful.

[stumpnc]

Mike on each side of the block you will see a tube at the top of each tube is a check valve. These are designed to be open at idle and vent the airbox from moisture etc ,when throttle is applied blower pressure increases and thes valves are supposed to close and let pressure build. If they stick open pressure will not build and you will have low power. They are made to take apart and clean.

[mpierce]

Originally Posted by Mikedriggers

Yes I used a dextron fluid..oil wise I used Delo 15w40. .

WRONG OIL!

You NEED a low ash oil. Get Delo straight 40 weight, as described above. The 15-40 can ruin the engine over time. CHANGE IT!

[Poohbear7278]

This engine don't have any electronics, 15w 40 will not hurt it, and it doesn't have a injection pump, the injectors are mechanical fuel injectors with a common rail fuel supply, check all the turbo piping and make sure the emergency shut off on the blower is not tripped it will choke off the air.

[twinboat]

With a turbocharged, plus supercharged engine, I don't think 2, little 3/8" airbox drains are the problem. Sure they can effect power, but not enough in this case.

[Poohbear7278]

Originally Posted by twinboat

With a turbocharged, plus supercharged engine, I don't think 2, little 3/8" airbox drains are the problem. Sure they can effect power, but not enough in this case.

Correct twinboat I ran these engines for years on equipment and never cleaned any drains . The rack could be stuck as previously stated from sitting but unlikely the only ones I ever seen stuck were stuck wide open which causes a run away engine which is the reason for the emergency shut off on the blower

[Mikedriggers]

Originally Posted by mpierce

WRONG OIL!

You NEED a low ash oil. Get Delo straight 40 weight, as described above. The 15-40 can ruin the engine over time. CHANGE IT!

Thanks mpierce, I plan on it soon

[stumpnc]

He stated that this has sat for 5 years. Mud divers , rats etc could have gotten all up in them,Who knows. When I found my coach in 2014 it had sat for 4 years after going through the entire intake system making sure it was clean, when I fired it up about a dozen dead birds blew out the tailpipe, along with nests,and all kinds of debris.

[Mikedriggers]

I have not found any tubes with check valves but did notice what they are calling a mini bypass blower. Here are some pictures..sounds like it does the same thing you guys are talking about on the check valves. If this valve is stuck in the closed position, will it limit my power? Working on removing it to check out.

[stumpnc]

Here You Go Air Box Drain Tubes

[Mr_D]

Originally Posted by twinboat

Last, is some of DDs have doors that closes, just above the blower. It is to shut the air down if the rack jams. Look for a lever and little latch that holds it open. It could be frozen and partially closed.

I came back to the thread to add the above but twinboat already did it.

[Mikedriggers]

It not letting me open it as is

[stumpnc]

Originally Posted by Mikedriggers

It not letting me open it as is

It should be in your download folder