Nissan LD28M running rough at low rpm

[DonGuy]

Hi,

My LD28M, in a 1986 Albin 27 SC, starts well and runs nicely, except that below 1100rpm it runs very rough. No smoke. A lot of vibration from idle up to 1100. Smooths out above 1100rpm or so. Rough whether cold or warm. Has about 3300 hours.

I'm hoping someone may be able to point me in the right direction to fix this. is there a usual thing that will cause it to run rough at low rpm?

I'm going to have the injectors cleaned, refurbished, tested etc.

I'm wondering if I possibly have a problem with the injection pump. yikes! It appears to be a Bosch VE. If anyone knows the exact model number, that would be really helpful.

Thanks,
Don

[jcollins]

Don,
I am by no means an expert but practical (and costly) experience has taught me to replace fuel filters. The costly part of my last excercise at DIY was a bad "O" ring behind the priming bulb/button. (I couldn't replace just the "O" ring.)
Same symptoms as yours. Rough/erratic idle up to 1200 RPM. Then finally one day it just wouldn't start.

[DonGuy]

Thanks. I've been reading a lot of stuff, and it is seeming like I may well have an air leak problem somewhere between the fuel tanks and the injection pump. Your o-ring would have created an air leak. In my case I'm suspicious of the Racor filters. One suggestion I've received for diagnosis is to install some transparent fuel lines at various points to see if there are bubbles. Lots of fiddling around ahead by the looks of it.