928 fuel help?

[amschnellsten]

hey guys, I just purchased an 88 s4 for pennies but it does not run. The car is in decent shape and I have narrowed it down as far as I know. I have no idea what number the fuel pump fuse is but when I energize the fuel pump relay the pump runs and then the car will start and die. So I have come to the conclusion that the Lh ecu is bad? I am not sure if this is correct but the car does constantly click when the ignition is on from the front of the motor. I have just dived into this and I did swap out the horn relay that works with the fuel pump relay and nothing happens unless it is jumped. When I bought the car the PO said that it has been sitting for a year and a half but it ran fine before it was parked. I have only made it this far because I used to own an 86.5 and an 87 s4. I missed both cars terribly and could not pass this deal up. I sold my manual 87 to buy a 84 Carrera and now I am back! Any help would be greatly appreciated. Where can I send the Lh ecu to get repaired and how much does this run or am i just jumping to conclusions and there is something that I should check first?

here is the car when I was bringing it home!

[MPDano]

Nice looking S4. How many Pennies if I may ask?

[Maleficio]

Exactly what my 82 auto was doing. Finally discovered the main ground for the L-Jet was loose. Not sure where the main ground is hidden for your model, but I would start there.

That intitial stumble is your cold start valve squirting with battery power. But since the injectors are not firing, the car won't run.

Seriously, hunt down your grounds, clean them, replace them, tighten the crap out of them. After that, if still no run, begin troubleshooting.

[Maleficio]

Also, verify that your ECU is actually connected, or fully seated. Have a look at the pins in the connector. Look for corrosion.

[Mrmerlin]

Nice looking S4 .

I would be checking/cleaning all of the battery connections then pull the lower bell housing off and check the flex plate to see if its preloaded,
then the crank end play measurement,
then torque the rear and front drive shaft bolts,
you can search for this as well.

You should do some searching for info here is a link for LH failure
http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=9&ved=0CGUQFjAI&url=http%3A%2F%2Fforums.rennlist.com%2Frennforums% 2F928-forum%2F516729-lh-jetronic-failure-with-happy-ending.html&ei=NFj1TsnpDoX9ggfOmvj-AQ&usg=AFQjCNFljDBvoqxqdE0hJNB3yaapp2KBXQ&sig2=LMZVU6CvxWkYZ5r1uw6r9g


NOTE your car does not have a cold start valve
Note running issues can also be caused by failed coil wires to one or both coils,
remove the coil wires and inspect the ends ,
if they are corroded clean them and make sure that they do not touch any parts of their run as they will abrade and short out.
Also make sure the ground wires are attached to each coil mount then to the respective cam tower or lifting lug

[1982_928]

Mine did the same exact thing, and it turned out that 7 of the injectors were clogged to the extent where nothing could get through. I let them sit with carb cleaner to break the crap loose and then blew it out. Fired right up and ran great.

I also wasnt aware that McDonalds sold 928's. Ill have to check next time i go there. (Hopefully never..)

[924CarreraGTP]

Replace the fuel injection relay, the fuel pump relay, and the fuel pump fuse. Suspect fuses and relays before you suspect the injectors or ECU being bad. ECU failure is common, but not as common as you might think. Sometimes it takes years for an ECU to go out completely. They can start with odd characteristics, and last forever before they quit. Of course you could go into the injectors and spend a week buying things that may not be the problem. It's up to you. I saw an S4 years ago that did this and turned out to be the Airflow Sensor. You won't know until you test some things. Hopefully you drained the fuel tank and put fresh gas in before trying to start the car.

[Landseer]

The Elkhart car? I took a pretty good look at that one.
It was complete, which was very positive, and priced right.
Its a platinum or meteor car that was resprayed white, which was the only downside.
Asking price was $2500 and they were begging for an offer.
I had the fusebox cover off / it and the brains looked dry, unmolested.
Congrats! Very good find.

There is a guy in Arizona named Rich Andrade who rebuilds 928 brains and maf.
I think I paid 325 for MAF rebuild and the price was 300 or 350 for LH rebuild.
I'd have the LH preemptively upgraded since its S4 and known to fail.
He'll also make sure you don't have those nasty authority aftermarket chips.
Just box the two brains and the MAF, send them for testing and repair, and get to work on the rest of the car.
(thats what we did for my 85, good thing too, as we found some unusual problems)

Also, John Speakes, a supplier on rennlist with some USA reps, does this test/rework stuff on 928 brains.
Careful, some of the 911 rebuilders are charging +$1000 for brain work, stay away!

24 year old S4 is not something that you patch, piece by piece. It needs refresh througout. They all need the same stuff it seems.
(there is intake refresh / hall sensor replacement in your future too, but it probably can wait, unless the rough running comes down to clogged injectors.)



On your car, if its the one I"m thinkng of, its too early to try to start it, beyond what you've already done.
(If you insist on starting it, at least turn it to TDC by hand and, look in the inspection holes and ENSURE the timing gears match the pointers -- you hope that old timing belt hasn't slipped cogs)

Lift it, check flexplate / thrust bearing endplay FIRST.
Chances are it will be ok --- I saw no aluminum on dipstick, but do this first.
If this is ok, then the car will undoubtedly run, so don't bother starting it.
Trust it.
Be safe, you don't want a 32V car running when its limping, and it will limp if you don't do the cleanup below:

Then, I'd do a complete ground and fusebox cleaning, and replace all relays 10 or 11 at $5 each.
Also all fuses. Replace with high quality buss.
On ground cleaning, I'd replace the rear bat strap with an advance auto $6 one for now.
And I'd pay extreme attention to the ground wires way down in the valley, under the air cleaner --- that's where your ECU's, maf, O2 sensor, crankpostiion sensor-- all the electronics ---are grounded ( not in the cockpit ). Its an Indiana car, right? Ground point corrosion is likely.

Check MAF wires, should be three in a triangle formation of filiments. Look at MAF plug and CPS plug for breaks / twists.

These days, I'm preemptively replacing the CPS on every 944 and 928 that darkens my doorstep. Its $65. Buy the bosch unit for the BMW that 928s rus sells -- saves $75 over the porsche bosch part.

I'd buy a fuel line kit immediately, too. Install that under the air cleaner. S4 is notorious for becoming an instant fireball. Rubber fuel lines / brittle / mechanic moving stuff around, boom.

I'd probably also do water pump and timing belt and tensioner rebuild right then, and clean up the coil ends and distrib caps in the process. That belt was changed once, but it was a long, long time ago. Get it running rough and its liable to break on you. 928Intl and 928srus are the places that I trust for water pumps, nobody else.

Coil end corrosion and distrib cap corrosion will take these down. Use a mirror and light to look into coil. BTW, coil ground wires are superfolous from a runnability perspective, they are for radio noise suppression. A good set of factory wires is probably going to be important. S4 coil wires as you might know tend to arc-out pretty badly, especially on drivers side. They even issued a TSB on it at one point and changed the wire length to try to fix the problem.

Anyway, good luck with the new car!

What are your plans for it once it runs?

[Danglerb]

What MrMerlin and Landseer said.

I'll add, have a good experienced 928, not just Porsche, mechanic give the car a thorough inspection. Some of the simple stuff you can do with a helper like all the switches, lights, etc., but plenty needs 928 savvy and time on a lift to find out what the big picture on cost to put it back on the road is. This may be an ugly amount, better to know it now than after you spend a couple thousand fixing it and adding zero to the value since it still needs twice that much to finish.

Dump the old gas and flush out the tank and lines, and put in a new fuel filter.

When you drain the oil, look it over, also cut open the filter and spread out the media in sun light.

Good luck with it.

[Landseer]

^^^ do this^^^ New tank strainer, fuel supply hose, fuel pump & fuel filter --- that just takes a lot of issues off the table.

[amschnellsten]

Hey guys thanks for all the responses. Landseer, it is the Elkhart car. I made them an offer that I could not refuse, I could sell the wheels and a seat dirt cheap and break even. I checked the timing belt and timing and everything looks fine for the time being (new belt and Wp are on their way) and there is no crank play. I will check the grounds and clean them up and check to see if there is any corrosion or play in the harness at the ecu. I replaced the fuses and the all the major relays last night and I am still in the same situation.

I will give a little more background on the fuel problem. I could KILL my friend for this but now I know that the car does run and sounds fine. When I dropped the car off at my "shop" and went to drop off the trailer, he had pulled the airbox and sprayed starting fluid in the maf and it started up instantly and oddly enough it idled perfectly smooth. I am not getting anything out of the fuel pump unless the the relay is jumped. If I jump the relay the fuel pump kicks on and the car will start and idle fine for having bad gas. The fuel pump fuse and relay are new now and I still get nothing out of the pump unless it is jumped and I still get this crazy constant clicking from the front of the motor at the fuel lines when the key is i the on position.

I need to get the bad gas out immediately! What is the best way to drain the tank?

[amschnellsten]

I just found this and it sounds very similar to my problem....... the clicking I am hearing is mentioned under method #2.

Starting Problems Trouble Shooting

[Landseer]

Well, like somebody said above, its probably the LH.

The LH has a circuit that triggers the fuel pump.

To drain tank you need to take the flexible line loose at the base of the back of the tank.
Have cans ready.

Oh, you could somehow have an inside tank and outside tank fuel pump in tandem.
Maybe Mr. Merlin could advise --- that could also be run killing issue!

The only hairy part of refurb of standard tank/single pump is getting the strainer unscrewed from tank. A bit tight for the 17mm tool, I used a thin walled socket. Problem is sometimes the metal tank insert breaks free.

[MPDano]

Lots of PB Blaster before turning that In-Tank Pump. If your worried about the IN-tank being an issue. Rid it. You can always remove all the in-tank parts and make sure to clip the electrical leads too so you don't accidentally re-hook them up. Just re-use the part that screws onto the Fuel Tank.

[Landseer]

Where are waterpump and timing belt coming from? This matters, potentially very much.

The fuel line replacement kit needs to be coming, too. That matters even more.

[amschnellsten]

Originally Posted by Landseer

Where are waterpump and timing belt coming from? This matters, potentially very much.

The fuel line replacement kit needs to be coming, too. That matters even more.

The timing Belt and Wp should be coming from 928 INt and My fuel lines will be made at a local aircraft shop I use quite a bit for turbo projects. You mentioned a guy in the southwest that rebuilds ecus do you have any contact information?

It is funny, i used to think that I had a good grasp of these cars but since it has been almost ten years since I have had one It is almost a complete learning curve again. I still have the exhaust I fabbed up, and Kinesis wheels when I had the 87 and I think I will throw that on at a later if this all works out. Wow this car brings back memories. Here is a link to my old 87
928 dyno run stock - YouTube

[Landseer]

Stan, above, provided a link of testimonials I just realized.
If you listen to anybody here, its Mr. Merlin.

http://www.electronikrepair.com/home.html

Sounds like you still have a good grip.
Well, in the ensuing time we've gotten a very good handle on thrust bearing failure. OEM clamp is too weak. Porken has a non-intrusive auxillary driveshaft clamp for $100 that you've got to install. I have them on two automatics. CRitical for S4, you've got to add this, or one below.

Constantine, a rennlister, has created monster extreme smooth replacement torque tube bearings. He also has an incredible driveshaft clamp. I have one.

Jim Morehouse collected WSM's with wiring diagrams, plus then collected dozens of factory-dealer specific 928 info and put it on a CD that can be had for $70. Incredible

It was determined that rebuilt waterpumps failed and bored the block, very bad. 928's Roger Tyson worked tirelessly to convince Laso to create new casting/improved plastic impeller at 1/2 to 1/3 Porsche OEM price. These are only two viable alternatives.

Master shop owner Greg Brown out in LA created a jig for repairing blocks eaten-out by waterpumps.

Roger also worked with Gates to fully define timing belts. The Gates belt and a super Gates belt for supercharged applications are both available inexpensively. Those of us with inexpensive, stretchy Conti aftermarket belts are replacing them.

Devek closed. 928sRus has become the leading new parts supplier for 928 due to complete obsession with the marque and direct porsche parts connection.

Thanks to Al Gore, we have incredible internet connectivity. Rennlist, Reuterwerks, 928OC and here are great USA based tech boards.

[924CarreraGTP]

Any 928 that sits for any length of time will probably need a fuel pump. There are two at a shop I work with right now that ran fine when parked but they both need fuel pumps now. I agree with these guys too, but make sure your fuel system is working properly. Many 928s that aren't running have fuel issues. As for the click in the front, you won't know until you go into it. Relays can click when they are going out. Get a long peice of hollow pipe and walk around it while it's running, find the click, and then report back as to it's exact location.

[waynestrutt]

From Harbourman

(All LH equipped 928s operate on a similar principle - a sensor (flywheel speed sensor) detects engine speed and crank position from a toothed gear at the rear of the engine. The flywheel speed sensor output is fed to the EZK/EZF (ignition) ECU. This gives the EZK the information it requires to time the spark
A modified version of the rpm signal is fed from the EZK to the LH ECU (and also the rev. counter). When the LH (fuel injector ECU) receives this rpm signal it will energise the fuel pump relay. The rpm pulse also times the injector signals from the LH ECU. Information on engine air intake mass (load) comes from the MAF (mass airflow sensor. From rpm and laod data, plus engine temperature and other sensor paramters, the LH ECU determines the correct fuel injector opening time)
Read the rest here:
Starting Problems Trouble Shooting

[amschnellsten]

landseer, thanks so much for the link! I talked to him today and he said he would rebuild the Lh and said from my description that is what it is. I was wondering if you or anyone else has had any dealings with Kuhn performance in Cincinnati? I googled the part number for my Lh and he has one listed for sale and he is local.