My 1991 vanden plas won't start appears to be getting no spark. I jumped the following relays 1 at a time and still nothing. Main, start(car turned over), fuel pump and ign on. I then noticed that my trans light in the instrument cluster (very top left side) is illuminated and stays illuminated when trying to start the car I seem to remember this light going out when the car was running. If you turn on the ign. but do not start the car should this light go out? Could I have a bad trans position inhibiting the car from starting?

 

Chainsaw:
Sorry, I responded to your other post before I saw this one. To my memory, the trans light stays illuminated until the car is running for a few seconds. I think that's a red herring.

I'm still unsure if you are sure you are getting fuel pressure and that the injectors are firing.

Scott

 

will check fuel pressure at the rail. I ordered a manual so that I can check pressures and voltages. I am thinking it could be the crank position sensor but I want to test it to be sure can't afford to just randomly replace parts.

 

Chainsaw:
I imagine that the CPS can be bench tested to see if it's working, but I've never done it. I can totally appreciate not wanting to start dropping one hundred dollar bills on parts without being sure! But that is one of the most common, and well-documented, culprits for a non-starting XJ40. Dig through archives to find out more.

I've heard that another quick and dirty test for the CPS is to see whether the tach needle moves when cranking. If it is registering a couple hundred rpms (on certain years, I believe post-90 cars), the CPS is supposed to be ok. If the needle isn't moving at all, it's bad.

I'm hoping others will chime in because I'm not really all that much help. Did you order a Haynes manual or go for the full JDHT CDs?

Scott

 

Thanks Scott I just ordered the Haynes manual (hope it has enough info) I will try watching the tach while cranking, actually makes sense that it would register while cranking. Thanks again

 

Okay while cranking the tach is registering about 200rpm so I am going to assume the cps is ok. will try to check the ecm for the coil to see if it is ok.

 

Chainsaw:
I'm sure the Haynes will help. I've gotten lost in everything you're already checked, and I'm not exactly a diagnostician (!!)... but I have a few more thoughts.

Regarding the CPS, I've read reports of guys replacing ones that appeared to be good (i.e. the 200 rpm cranking test) and solving the problem. So, that's just a quick and dirty pointer, not to replace a bench or replacement test.

You mentioned earlier that you jumped the fuel pump relay, which would help you discover whether the fuel pump itself is working. But what if the relay is bad? You can swap in another relay from a non-essential component to find out.

You will need to have 40 psi of fuel pressure at the rail for start up. If you haven't ruled out this being a fuel related problem, you'll want to have that checked. I will say only observationally, that most non-starts do seem to be fuel related rather than spark. Others may disagree...

Then there are all the 'tune up' possibilities: the coil itself, the HT lead to the distributor, and, frankly, a cracked cap or rotor. All stuff I'm sure you know, and common faults.

Btw, keep a good charge on the battery especially with all this cranking. These cars are notoriously sensitive to that. A low battery has been known to cause the very problem you are trying to correct!

Best of luck. I truly hope others might be willing to share more helpful advice than I have.

Cheers,
Scott

 

Be sure to test the ignition module somewhere by distributor on top of frame ( I think it is a GM cross part ).

 

Guys thanks again for all the help I have replaced the cap and rotor and ohm'd the wires. I will see if the manual has test for the cps and the ignition module. I have not verified the fuel pressure and you are right I should probably check that as well. I think a stab light on the - terminal of the distributor should flash while being cranked if it is getting the proper signal?. Thanks again