XJS on startup revs to 3000 plus

Those on this forum that helped me out on the coil wiring I thank you. The XJS now starts but revs to 3000 plus on start up. I immediately shut it dow, found a disconnected vacuum line but made no difference. At the moment the rear air lines from the air pump for pollution control is off at the check valve connections. Would this cause this. If not, any suggestions

have you checked the butterflies are closing properly ?

the air pump won’t do anything as the air is pumped to the airbox , so before the throttle

If there’s no mechanical problem holding the throttles open then you have a lot extra air coming in from….someplace else.

By chance do you have the air filter housings off the car? The ones that bolt to the throttle bodies? If so the open bolt holes will create a large vacuum leak


That was the act Doug. Thanks for the heads up. Can you tell me where to buy the vacuum hoses on the manifold cross over pipe, mine are shot. Michael

Are you taking about these?

Wow. You can buy coolant hose for about $2.50 foot online. All you need is the OD of the cross-over pipe, and order hose with the same ID. SD Faircloth

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I recommend the oem crossover hoses. They are extra hard, and stand up to oil vapor. Coolant hoses will eventually go soft and collapse on high air volume. Same for AAV hoses.

I even tried silicone at the crossover, but could not get perfect angle, and they are tough to get a good tight clamp on.

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I purchased a reinforced fuel hose with a 90 degree bend, recommended on this site, cut it in half and shortened the ends and it worked out just fine for $29. Michael

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