Engine dying randomly.

greenmeanie · Post by **greenmeanie** » Wed May 16, 2007 2:58 am

Gents,
I'm having problems with my 101's engine. It has been rebuilt recently and is now set up as a 9.3 CR 3.5L with the original ZS175 CD carbs.

The symptoms are that she will start like a champ, idles well and initially pulls well. I can rev her in the driveway and she runs well. After about 1/2 mile it feels like she is being starved of fuel and sounds almost like one carb is no longer working. This happens quite suddenly.

I've checked with the AFM and she is going lean and not flooding. I've pulled the top end of the carbs and checked them, jumped round the oil pressure switch, replaced the fuel pump with a spare, changed or cleaned the filters and blown the lines clean. I also set up the timing to 6°BTDC and made sure the vacuum advance was working. She has a Newtronics electronic ignition in place of points.

The big question is what could be causing her to die like this. WHen getting her through emissions this year the mechanic said he reset the float heights. If he reset them too low could the engine be running fine at idle but be unable to keep up with fueling at higher rpm?

I'm getting pissed with this problem as it just won't go away.

Cheers
Gregor

ChrisJC · Post by **ChrisJC** » Wed May 16, 2007 11:53 am

When she's running badly, is there any chance you can find out which cylinders aren't firing properly? Maybe have an assistant pull leads (with suitably insulated tools!). If it's in the pattern 1,4,6,7 or 2,3,5,8 it will be one carburettor, and a quick look at the manifold will tell you which one it is.

Chris.

jrv8 · Post by **jrv8** » Wed May 16, 2007 12:06 pm

Hi,
When you increased the CR on this engine, did you change the needles in the carbs to suit ?
The problem sounds like too lean a mixture. When it starts to run poorly , does pulling out the choke slightly make any difference ?

Regards
Jim

greenmeanie · Post by **greenmeanie** » Wed May 16, 2007 2:27 pm

Yup,
I modified the carbs to take SU BBC needles as the options for ZS were extremely limited. I wasted time with Burlen as they had a very nice catalogue of needles but when I tried to order they couldn't actually provide more than a handful that were going to be too lean anyway.

My next steps are to run an electrical feed to the pump straight from th ebattery to make sure that I do not have a bad ground or short. After that my only other idea is to pull the fuel cap and run her to make sure that it isn't a blocked tank breather.

Cheers
Gregor