Need Help starting my JAG

Bought a nice 1985 xj6 Vanden Plas series 3, tried changing the fuel pump and cleaning out the fuel system,changed the battery and several elctrical system parts, and it hasnt started ever since I bought it and I would like some tips and imformation from experienced owners to help me get it running soon
VIN: SAJAY1344FC397724

Hello Angel - when you say ā€œit hasnā€™t startedā€, do you mean that the starter has not been able to rotate the engine, or do you meaning that the starter is rotating the engine but the engine will not run - Tex Terry, II 1991 XJS V12 Classic Coupe, 1986 XJS V12 Coupe - 4/10/2020 2044hrs EDT USA.

Was it running when you bought it ? How long ago ?

If the engine doesnā€™t turn:
http://www.jag-lovers.org/xjlovers/xjfaq/nocrank.htm

The first thing is to determine if itā€™s because you donā€™t have fuel or because you donā€™t have spark. It could be both ofcourseā€¦
http://www.jag-lovers.org/xjlovers/xjfaq/nostarts3.htm

http://www.jag-lovers.org/xjlovers/xjfaq/index.html

1 Like

First, test for spark (remove the centre lead from the distributor and position it 5-10mm from the cam cover, let someone crank and see if you have decent spark).
Second, put the transmission in drive and turn the key to crank (get someone else for that). It wonā€™t power the starter, but the fuel pump will run. Now, with the fuel filler open, push down the little flap and peer down the neck: if you can see return flow, assume fuel pressure is at least there.
Third, locate the wire that runs along the wiring loom at the side of the water rail where the sensors and injectors are, next to the inlet cam cover. Turn the key to ā€šrunā€™, Dis-and reconnect the bullet connector. When you can hear clicking every third time (donā€™t count), then assume the ECU (Computer) is alright.

When it is cold and the cold start injector is not working, it may take a minute or two until it starts, so instead try starting fluid and see if that makes it catch.
Also, make sure the throttle body is closed aka has a small gap of 0.002ā€œ.
Good luck
David

it rotates the engine but it will not runā€¦

and no it hasnt run even before i bought it, thought it was an easy fix but turns out it wasnt. bought about 2 years ago and thank you I willl take a look at the linksā€¦

Hello Angel - good to hear that the engine does rotate with the starter - after you have had a chance to read through the information, contained in the links posted to you, donā€™t hesitate to come back with your questions - many knowledgeable, and ready to help, listers are on here - Tex Terry, II - 1991 XJS V12 Classic Coupe, 1986 XJS V12 Coupe - 4/11/2020 2059hrs. EDT USA

thanks for the great trips will try them all

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I think it is prudent to run a compression test, Angelā€¦

With an unknown engine; the compression test will confirm that you are not whipping a dead horseā€¦:slight_smile:

Frank
xj6 85 Sov Europe (UK/NZ)
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Angel!
You need fuel, spark, and compression.
Check for spark at the spark plugs when you rotate it.
Check for fuel at the fuel lines.
walter

One of the most common problems is the fuel inertial cutoff switch. This is designed to sense a collision and shut of power to the fuel pump to prevent a fire. Check to see if you are getting power to the fuel pump. If no, the culprit is, if I am not mistaken, located in the right side of the passenger foot well at the bottom of the A pillar. If defective, replace or bypass.

I have got it to run not to long ago but it would die out when accelerated, now it doesnā€™t want to turn on again. I tested the injectors and cleaned them up because they were clogged, maybe it could be the pressure regulator, anyone know how to test it out if the car with out a gauge?

If it hisses when the pump has built pressure and holds the pressure for hours it should be good.
I think you blew off a hose or so when it was running lean and didnā€™t accelerate and now itā€™s too lean to start.

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It may also be a weak fuel pump, Angelā€¦

A crude pressure test; open the filler lids and run the pump - if there is no return; itā€™s likely a weak pump. There is no viable way of verifying fuel pressure without a pressure gaugeā€¦

However, this is also a possible symptom of an air leak. Remove air filter; with the engine idling, gently push in the AFM flap. With an air leak the engine rpms will rise - otherwise, even the gentlest of movement; the engine will misbehave if fueling other wise is perfectā€¦

Further; the fuel lines may be clogged - with the engine misbehaving; instantly change to the other tank. If the engine instantly recover; insufficient fuel flow from the ā€˜offendingā€™ tank is likely. And if the filter is clogged; engine starves at higher consumptionā€¦

But symptoms doesnā€™t exclude other causesā€¦:slight_smile:

Frank
xj6 85 Sov Europe (UK/NZ)
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