Old Feb 26, 2025 | 08:47 PM
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80s-new-man
Sierra Sapphire RS 4x4
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Joined: Feb 2023
Posts: 39
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From: Norfolk
Default Help, sierra v6 cranks good but will not start

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
update:

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!

Last edited by 80s-new-man; Feb 28, 2025 at 08:13 PM.
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