How to get a 928 running.

924CarreraGTP · 924CarreraGTP's Garage

Disconnect the battery. Drain the tank from the bottom. Flush it out a few times with several gallons of fresh gas mixed with a small amount of B12 Chemtool. Plug the tank back in. Fill it with gas and a very small amount of B12 to break down the sludge in the fuel lines. Pull the lines from the back of the fuel rails. Take old cake icing containers and cut holes in the lids and push the fuel lines into the holes so the old fuel in the lines will go down into the containers without splashing or spilling. Prepare a water hose and a fire extinguisher for safety. Disconnect the ignition coil. Turn the engine over. If fuel flows into the containers, Score! Let it push the old gas out at least enough to clear them. If no fuel comes out replace the fuel pump relay, the fuel pump fuse, and replace the fuel injection relay. Turn the engine over again WITH THE WATER HOSE AND THE FIRE EXTINGUISHER HANDY. If no fuel comes out, replace the fuel pump and filter. Turn the engine over. If no fuel comes out double check your relays, fuses. When you get fuel flowing, let it flow and run into the containers. The fuel will be amber colored from the 8 years it sat in the fuel lines and turned to varnish in the junk yard. Get all of the amber colored fuel out until it turns into fresh gasoline. Reconnect the fuel lines correctly. Disconnect the fuel pressure regulator, connect hose to the fuel rails and push clean fuel through the fuel rails past the injectors into containers. This washes the varnish PAST and off of the injectors.
Reconnect the fuel pressure regulator. Reconnect the ignition coil. Turn the car over and see if it fires. If no fire, start checking sensors and test for spark AFTER THE GAS AND FUMES HAVE EVAPORATED. Check Jetronic!
Why do so many people work backwards or tear down the whole fuel system? When you add pressure washing to a fuel tank, you add water in a place where water shouldn't be. The 928 is a pretty simple car to understand. If I left anything out please tell me. Please don't say anything about cleaning or renewing injectors or injector lines. How about getting the car running before you start replacing things that aren't broken? Just my two cents. I never post new threads so I figured why not.

Mrmerlin · 11-12-2011, 04:50 AM

FWIW the injectors will usually clog after sitting for a long time,
so after the first part of the fuel supply is cleaned out then the injectors will be the next part to cause issues,
and even after cleaning them you may still have them get clogged as more deposits from the fuel system can find their way into the injectors,
best thing to do is drive the car a lot to continue the flushing process, add techron to the fuel as well.
Also consider doing an oil change after a few tanks of fuel injector cleaner has been used

Landseer · 05:02 AM

That's one way, not mine.

I drain everything, remove all fuel lines, replace pump and filter and gas tank screen when cleaning the tank. Clean the tank. Don't even bother trying to start the car or cycle the system beforehand. 3 of mine were bought completely non-running, never turned over before the sale.

New fuel lines (crucial), and do replace injectors or send for cleaning. Reason --- a) they are often clogged, b) if they are partially clogged, like on my 85 32V car, you will struggle for months and subject the engine to knock conditions as you stumble through all the troubleshooting.

Pull electrical panel, do all ground point cleanings, new battery, 14 pin cleaning, be SURE to empty and vacuum the nut shells out of the alternator duct before turning the car over --- otherwise they jam in the cooling fan blades and esp. with Rhone units, will rip the diode electrodes.

If you can't afford to replace the wear parts and you are so ADD that you can't wait to start the car, then have a talk with the mirror. Methodical, slow, smart. You know its going to run. Wait for it.

Am now pulling injectors and either replacing ( if 85 forward ) or getting them cleaned ( 16V cars ) because of experiences not being able to get them running due to clogged screens. For 32 V 85/6 cars, there are a couple of great, cheap injector options. I used a set of ford motorsports bosch design III units that cost less new than the cost for Witch Hunter to clean and ship the old ones.

aluminum · 11-12-2011, 06:06 AM

After Cleaning any Porsche 928 Full Tank with a Pressure Washer if you don't know to dry out the Tank after Cleaning > ? Hummm Tip it up to drain in a warm place ( Sun is good ) a leaf Blower / Fan > some few hours and the tank will mostly be dry enough > a few drops of water sill inside will not hurt anything in fact.
***
And Yes you will find a Large amount of sludge in the bottom of the tank you will discover >> This sludge will continue to Pumped into the Fuel System over time unless you clean it all out .
I agree . to get a Car running so you Know what it needs cost wise is a good Idea >> however a
"Partial " Cleaning will result in ongoing Crud ( to use a word lol ) being pumped into the system.
If that Happens Your back to Square one > want to start all over again > I don't think so .
************************************************** ***************************
One can Get a car running many ways > the point is to keep the car running < and with a High Pressure Injection System that Means Clean.
Filters are Cheap so after cleaning and the car running to change the filter every 1,000 miles some 3 times is a good investment .Only about $60
***
Some Injector Cleaner in the fuel will not hurt as a bit of crud in the injector's may wash away after some few tank's of clean fuel. Most non properly working Injectors still pass fuel but they don't Spray it out in a proper pattern but rather just drizzle or Drip it out thus causing poor Millage and performance . This may not matter to some but perhaps they should tell people they have a
" Pusher " rather then a " Porsche " in that event .
Happy Landing >

Landseer · 11-12-2011, 07:19 AM

The little inlet screens on the injectors can get pretty clogged with grit that doesn't flush-through with cleaner. The rebuilder replaces the screens and pintle caps during the process.

If you are into the 928, then even if you discover the engine is not salvageable, you remove the parts and save them for your next car. Its never a loss.

Just a parallel set of ideas, it all works out in the end.

Danglerb · 11-12-2011, 11:44 AM

Are you guys sure?

Why not hook up some jumper cables, pull the air filter and spray some starting fluid in to get er runnin?

*** Chase out possums with a stick first.

924CarreraGTP · 924CarreraGTP's Garage

See this is exactly why you open the pressure regulator and circulate the fuel and chemtool past the fuel injectors. If you don't believe in the power of B12 Chemtool, drop an old dirty carburetor in it. It will eat ten coats of paint off of metal in 4 seconds. You can flush the fuel tank out with gas and chemtool and it will dissolve the crud and wash it right off the plastic and out the tank. Plug it, fill the tank with this solution (gas and chemtool) and I do mean fill it! Shake the rear of the car violently. My 928 has never had a plugged injector, and it starts within 2 seconds every time. What do you think a few drops of water will do to fuel injectors?

Danglerb · 11-13-2011, 12:18 AM

Drops of water could be bad, but all fuel tanks get some water in them from the air as it cools inside the tank. Gas and water don't mix, but water and alcohol do, so any amount of alcohol going through the fuel system from time to time should remove the water, either by bottles of "stuff" or I suppose using pump gas with whatever it is they put in these days.

I drained my tank, pulled it, and washed it out with Simple Green or Purple stuff, blew it out with air, and left it in the sun for a day. No issues.

924CarreraGTP · 924CarreraGTP's Garage

This is true about the sweating inside the tank. I know this from Mercedes Diesels. When the tank sweats it causes condensation and clogs the fuel filters. It requires two new filters about every fall or winter. I agree about the alcohol. HEET is a good one for that. You can also make test batches of biodiesel with HEET.
Barryman's Chemtool was something I became a believer in when I was still working on 1960's Triumph motorcycles. Gummy fuel systems are a big problems in english bikes.

I also agree with the ground cleaning and especially a new battery. 928 electronics can lie to you when the battery is not in great new shape.

Danglerb · 11-13-2011, 10:09 PM

BTW local guy just finished a full restoration of a 49 Vincent Rapide.
Nice picts for English bike likers.
1949 VINCENT RAPIDE - ULTIMATE CAFE RACER - FULL CUSTOM RESTORATION

924CarreraGTP · 924CarreraGTP's Garage

Nice bike, but I don't like the tank. An original Vincent tank and bright red paint would make it much more interesting. I like the aluminum wheels. I have a lot of favorite motorcycles. One is the 1966 Triumph T120TT Special. I also like the Hesketh Vampire, the Vincent Series D Rapide, and the Norton Commando Fastback. If anyone knows the whereabouts of a 1960's Triumph please let me know. I'm looking for another one.
I've always owned Porsches though. I've had 924s, 928s, 911s, 914s, and 944s. I think I've owned my last 944 though. The Motronic is troublesome in the 944s. The handling is superb, but the 928 can match it if properly prepared. The 928 is a much better car quality wise. I like the sound of my 911, but I couldn't drive it daily. It's too ancient.