bigmac

Hi Y'all,

Chaadster here on behalf of Bigmac, whose '90 cranks but won't start...

I've gone through the fuel pump relay thing by swapping out the horn relay, with no change. I hear the pump run, and I smell fuel, so it looks like that's working.

I've affirmed all of the relay connections by wiggling them and reseating them. No start still.

So, my question is whether or not there's a way to test for a faulty LH or EZK relay by jumpering or other means?

Any help is appreciated!

IcemanG17

Since the fuel pump is running......you can jumper the EZK relay...but it doesn't fail all that often....my guess is its something else.....

http://www.electronikrepair.com/

Rich has lots of no start tutorials on his site....he also can email ya a 9 page file that covers EVERYTHING....I have it around here somewhere if ya need it too....

WICruiser

You can jumper all three of the critical relays to confirm if it is a relay problem. Given that the pump is running you could just jumper the other two.

Alan

You can test the relays by activating them in the horn location - however the coil may not be getting activated for some reason on these in their normal locations and a jumper between 87 & 30 in the empty relay socket will verify if that is what may be stopping the relay from switching...

You can buy or make relay test gear that shows you if the coil is getting activated - sometimes these are helpful for debug - but its a very expensive way to go for occasional use...

Alan

AO

Chaad, let me know if I (or more specifically, my car) can be of use... but actually, yours should work too.

John Speake

If the fuel pump is confirmed as running when the engine is cranked, then is most likely that you also have spark (best to double check.)

Therefore no LH or EZK relay problem. The issue could be a short on one of the injector connector wires.

Alternatively, there may be some damp or other issue with the plug/coil leads. Don't forget that a 928 will very quickly flood if it is being cranked and getting fuel into the cylinders, if it doesn'tr start almost imeadiately. It can take a very long time for it to dry out unaided.

Suggest - remove fuel pump relay, crank engine with foot to the flooor until it fires on some cylinders. When it stops running, jump the FPR for a second or two, remove jumper, repeat the start, always with foot to the floor.

Finally, fit the FPR again start with foot to the floor, keep it running while it finally clears.

Jim bailey - 928 International

Could be an issue with the ignition monitoring relay the clear small box attached to the LH Brain box. That relay has the ability to shut down 1/2 of the injectors if the exhaust head temperatures are to far apart. That means it can also fail and shut down all 8 . Crank the engine and pull a spark plug to see if it is wet with fuel.

chaadster

thanks for the replies, insights, offers, and tips everyone. I'll report back once I can get to the car again, hopefully in the morning.

I've got the guy from Winding Road breathing down my neck to get the car to do the Modern Classics column feature, so this is an untimely issue that I want to resolve ASAP.

FlyingDog

Make sure you are getting 12V to both relays. I'm not sure about cars as late as 90, but earlier cars have a separate 12V feed through the rear harness for the computers.

bigmac

Bump to PAT

Red UFO

This what was wrong with my shark. I thought it was the fuel pump relay but Rich was able to quickly figure out it was the LH relay. Fired right up when it was jumpered.

bigmac

The tow truck came and the driver insisted on trying to start the car and on the 15+ turnover it fired up and come to life,
after driving a few minutes it runs as normal. Any ideas?, bad gas?, car left too long alone with the Chaadster?,
What should I have the mechanics at PAT check?

Thanks, Mac

Red UFO

Just because it started this time don't mean the problem is fixed. It will most likely keep happening and leave you stranded somewhere in the near future.

IMO these relays start going to hell and randomly decide on there own they work or not.

Your best bet is buy 4 new relays and put in new ones for your fuel pump, EZ, LH, and starter. Leave the 4 used ones in your car just incase. There only $12 each.

This way all your ****s brand new, its cheapier to spend $50 now, then $100 later on a tow.

bigmac

Red, Appreciate the advice. Car scanned O.K. and appears that it was flooded sitting in garage. Runs great now and starts normally

AO

Mac-

A new set of plugs might be in order. It could be that they're a bit fouled now. Just a thought.

-AO