hey guys,


Im almost there....

I have a 97 tj with fresh built OM617 with M pump.

I have had some issues Primming the engine, and have eventually got it primmed and running. this was over an extended period of time. I added in an electric fuel pump to help.

once running and on the highway she runs hard building great boost, and awsome power, but i was having issues on the bottom end having extremly poor power untill it reached 7lbs boost then blink and I was at 20lbs.

I started driving it to try and figure out what as up.

I drove it for 3 days to work about 35 miles each way, and was enjoying it.

today i dug into a couple issues, the first being starting

I adjusted the timing and that helped, went and got fresh fuel and it started staling when I would slow to a stop.

upon arriving home I started poking around the fuel lever limited by the external alda and that moves with the vacuum fuel shut off seemed to be in an odd position ( it was not sitting against the limit screw) i moved it a bit while the engine was running and noticed the Idel changing up clockwize and killing it counter clockwise.

after further poking about i came to the realization that my cranking sue was due to the shut off valve was almost closed and not allowing fuel through.

further poking revieled it was sticking and not returning to open, after cleanning and lubing and repeated activating it seems to be functioning properly.
Score.

my low idel Power issue is gone too.

onto the next issue, restarting

now that it starts and stop MOSTLY and some further poking about, it would not start on the fist time I tried , it would only start on the second time i turned the key every time.

in here I tred to use a Spring to return to open but it would inhibite shutting off I tried diferent spring and came to the conclussion the spring was not alowing the shut of plunger to move from vacume.
I even put a vacuum line on to suck which is when things got intresting and I realized and could her the shut of Plunger actvating and see the Lever moving.

I went through repeated cycles, and everything appeard fine, removed the spring , hooked up the vacuume shut of it started and stoped as it should and THE WOULD NOT START!!!!

then it would start on the second turn of the key.

onece running and then shut off the vacuum would activte the shut down lever, and on the fist tie starting the shut of lever would remain in the off position, untill I shut the key off and then back on at wich time the vacuum would release and allow the engine to start

so if any body has read this far and acan follow, any ideas as to why the vacume wont release?

thanks in advance

 

I havent got that far yet with my TJ, but I'm going to use the Mercedes soleniod (once I find it, LOL!) Are you using the Mercedes vacuum solenoid? Or something else? I'm assuming the Mercedes solenoid has a bleeder of some sorts to release the vacuum. I will have to look tomorrow if its not raining. I have it at my shop thats about 30 miles away.

 

Ok, pulled up the vacuum line drawings on the 300d shut off, Mercedes uses a mechanical valve actuated by turning the key cylinder on the ignition switch. You obviously dont have that on the TJ, so I'm assuming you are using an electric solenoid valve. Getting late, so I will work on a easy solution tommorow, but not hard to do. I have seen a lot of post leaving the solenoid energized once the engine is off, but that is a good way to run down the battery.

 

Ok, I get to thinking about something, then I can't sleep until I find a solution! LOL! This should work for the restart problem, I'm going down to Advance in the morning to see if it will work the way I want it to. What you do, is reverse plumb it. The vacuum side of the check valve is left open, one of the two ports on the other side goes to the shutdown vacuum line, the other port goes to the load side of your vacuum solenoid. This should give you full vacuum on shut down, once the solenoid is de-energized, the check valve will allow the the diaphram to suck air back into the circuit allowing the diaphram to return.

 

hey Hillbilly1
thanks for the reply.

I am using the stock mercedes vacume swtch controlled of ignition power. it worked fiine with the MW stock pump.

so when i shut the Jeep off now, it shuts off fine.

when I go to restart, the vacuum is still present until i turn the key to start then back to off at that point the vacume releases, and the jeep will start fine.

 

Sounds like the vacuum is not bleeding off until it is cycled. Is it wired to stay energized the whole time the engine is off? Or does it apply vacuum when it is de-energized? The diagram I pulled up shown a mechanical actuation instead of electrical, so I don't know which logic they are using, fail on or fail off. The Mercedes may have a one shot timer that turns off power to the relay after a predetermined time. I will see if I can dig up a valid wiring schematic on it.

 

Ok, after lots of searching, not finding a lot out, all of the diagrams are for California versions, but I did find the Mercedes soleniod is normally open, closes when voltage is applied, from what vac schematics I could find, it looks like its tied in before the main check valve on the vacuum pump. Worst case, you could try the $3.00 check valve to see if it eliminates the problem. It's raining all day here, so it doesn't look like I will be able to see how everything is connected on the donor car.

 

k i figured it out!!!

I used the vac switch on the Right, and it worked fine on the MW pump for some reason when I went to the M pump it did not work.

While going through my parts bin, I came accros a pair of other solinoids the metal bodied Round one on the right, I tried that, and it apears to vent when swiched off.

everything is working as it should now!!!! starting real quick and shutting off instantly

up next id getting EGTs under control.

little grean thing on the right is amercades vacume check valve, thes a tone of these on the car

 

Good deal! I got to track my vacuum line back to mine so I will have the right one. Apparently it is a dealer item, as I couldnt find any for sale on the web to see what it looked like.