Hi there,
I’ve had the engine on my 1992 XR4x4 2.9 rebuilt 7 months ago but has been running rich until I get the emerald ecu fitted. As I knew this I decided to clean plugs the other day. Today I took both lambdas out and cleaned them with carb cleaner.
All put back & didn’t touch anything else.
coming to start several times , I get crank and the occasional cough but no fire up.
i thought maybe the fuel pump had gone but I notice the no.6 cylinder exhaust outlet manifold is quite hot despite never firing up, whereas all others are stone cold. I guess that means fuel is getting there, but don’t get why the manifold is hot on only one branch.
i checked all fuses and ok.
all injectors were completely reconditioned.
im at a bit of a loss as she started first time and although ran a bit rich and lumpy because of the race cam, she never failed to start and run.
Grateful in advance for any ideas, cheers Stu
updated: I realised maybe it should be in Q&A so I put it there.

 

If I'm reading this correctly, all was well before you cleaned the various items.

Perhaps start working backwards, check the electrical connections on the lambda.

Could yOu have damaged or dislodged a plug lead off the coil/dizzy?

Doesn't sound mechanical.

Bad fuel?

 

Check for spark at the coil and plugs

Spray some easy start up the intake

 

Thanks for the advice! Yep checked those things - I didn’t check the plugs, as I’d only had em out a week ago & cleaned. However I take em out again and they were covered in fuel. My conclusion is, running rich for 7 months has mullered them, because as soon as I fitted some NOS motorcraft plugs she started and ran first time. Cheers have a good weekend!

 

Glad you got it sorted, it is nice when a simple solution solves the problem.

 

If the timing’s off even slightly, that can also cause starting problems. You mentioned cleaning the lambdas with carb cleaner, they could be damaged, which might mess with the fuel/air mix. Also, even if the fuel pump seems fine, low fuel pressure could be a problem, so it’s worth checking that.