Looking for Help

[ctgreg]

Hey all,

I had my 1990 out yesterday for a drive and all of a sudden the SES came on. I drove home and ran through a few things. One thing I noticed is that the vacuum pump is running non-stop when ignition is in the "on" position, but it appears that it's not running when car is running. I pulled a Code 16, but for some reason I can't seem to correlate one issue w/ the other. I tried clearing code, but no go.

I also checked all vacuum connections and I can hear one connection in under left front of plenum where two line are attached.

Any and all advice would be greatly appreciated.

Thanks in advance,
Greg

[jonszr1]

sounds like you should pull the plenum to find the leak.if you havent done it its really easy .do you have a factory service manual? also before you pull it order a set of gaskets from jerrys gaskets . hope this helps . ps i am unsure about why you pump doesnt work with the engine running

[Jeffvette]

Code 16 is a DIS system fault. You need to get a manual and follow the diag tree.

The vacuum pump running is a issue in the fact that you do have a massive leak, but the engine when running creates enough natural vacuum to keep the tank stored. If you did get into the secondary system for a lengthy time, you would set a SES light for that as well.

[ctgreg]

Code 16 is a DIS system fault. You need to get a manual and follow the diag tree.

The vacuum pump running is a issue in the fact that you do have a massive leak, but the engine when running creates enough natural vacuum to keep the tank stored. If you did get into the secondary system for a lengthy time, you would set a SES light for that as well.

Thanks,

I have the manual, but for some reason, the vacuum issue doesn't equate w/ code 16. I'll have to dig deeper.

Greg

[ZZZZZR1]

Thanks,

I have the manual, but for some reason, the vacuum issue doesn't equate w/ code 16. I'll have to dig deeper.

Greg

Greg,

Are you busy on the 27th of March? We have a get together and "tearing down an LT5" then!

http://www.zr1.net/forum/showthread.php?t=11189

Hope you can come out and meet our group!!!!!

:thumbsup:

David

[Jeffvette]

Thanks,

I have the manual, but for some reason, the vacuum issue doesn't equate w/ code 16. I'll have to dig deeper.

Greg


They don't equate. Troubleshoot separate.

[Hotrod]

There is a small check valve on the vacuum pump hose, under the plenum, to prevent the pump from trying to pull a vacuum while the engine is stopped. Sometimes this valve goes bad. Try disconnecting to line at the fitting where it goes under the plenum, drivers side, and place your finger over the line (non plenum side) and see if the pump stops running. If so, you can add a small check valve to the line, in series, and prevent having to pull the plenum.:mrgreen:

[ctgreg]

There is a small check valve on the vacuum pump hose, under the plenum, to prevent the pump from trying to pull a vacuum while the engine is stopped. Sometimes this valve goes bad. Try disconnecting to line at the fitting where it goes under the plenum, drivers side, and place your finger over the line (non plenum side) and see if the pump stops running. If so, you can add a small check valve to the line, in series, and prevent having to pull the plenum.:mrgreen:

Thanks Rod...already fixed. I think something got really wet when I rinsed the car off at the car wash. I recently checked codes and got a secondary code 61. Seems fine now.

Greg

[GOLDCYLON]

So your still getting a code 61 ? Or???

Im getting an intermitent code 61 that wont hard set SES will illuminate then go away. Im wondering if my vacuum pump is bad? From what I read in the FSM if the pressure on the secorndary actuators hits a set point the pump is suposed to kick in to maintain pressure. Anyone ? ?

[scottfab]

if pump stops when disconnecting hose etc as already mentioned then take the car for a drive and get into the secondaries for 10 or so seconds. If the HP drops noticeably at about 8 or so seconds then there is a problem with the vacuum getting to the actuator(s) or the secondary fuel pump is failing.