Damn thing wont start

[Brando]

I knew it was bound to happen. Here's what I got:

This evening, turn the key, fires up for a second then dies. Cranks over, has compression (*chirp-chirp-chirp-chirp* when cranking).
-I know the DME relay is working... felt the contacts inside click over when turning the key on and turning to start position.
-New DME Relay
-New ignition switch.

I have yet to test for spark, and I can hear the injectors click when cranking (one arm through the window, head in the engine bay).

My guesses are:
No fuel (fuel filter plugged or pump not running).
No spark (bad coil).

Thoughts? Guesses? Suggestions? Fuel filter is definitely getting done tomorrow, but if necessary I can get replacement parts before tomorrow (wednesday) is through. Thanks in advance

~B

[Razorback1980]

Hey Brando, before you jump out and start buying parts, let's see if we can figure it out. I can't remember for sure but I think when you turn the key on, you should hear the fuel pump start run for a brief period. That's the first clue whether it's the fuel system or not. The best way to test for fuel is with a fuel pressure gauge. But some of us don't have those so....(Make sure you NEVER try this when the car is hot), but I have seen some people crack the fuel filter fitting on the front side of the fuel filter and then turn the key on to see if gas starts spraying out the connection or not. That works although make sure you are not within spraying distance of the connection. Not the best method but it does work. If the gas has pressure AFTER the fuel filter, then your filter is at least letting enough gas through to start the engine but it still may need to be changed. If there is no gas pressure there, either check the fuel pump or crack the fitting on the back side of the filter and see if there is pressure before the filter. If you have gas pressure everywhere, then we'll assume that it is now a spark issue. Let me know what you find on this and if it's not the fuel system, we'll work on the spark problem.

[ae1969]

Are you saying it runs for a second......... if it fires I would check the plug on the AFM see if it has popped loose.

Otherwise you need to follow some systematic troubleshooting....... its pretty straight forward.

You can easily check for spark with an extra plug.... 1 minute test will confirm if you at least have that.

[Brando]

Thanks guys Here's how I'll do it...

Since I already have to put a new fuel filter in, I'll jumper the DME Relay slot to run the fuel pump. If I don't hear the pump .. uh ohs! If I do hear the pump... Okay it works. I'll have the exit-side of the fuel filter going into a can to see if any fuel comes through. After a filter replacement it *should*.

I'll also grab an extra plug and test for spark. How do you check if your coil is bad? 12v across the + side and ground (engine block)?

It's ironic how this happens after I renounce buying parts for the next few months so I can afford paint... Ugh..

[SoCal Driver]

Check the plug on the AFS as previously noted.

Might want to check for spark before you check the fuel manifold. Take that spare spark plug out of the glove box, pull the connector off of the first spark plug, stick the spark plug in, lay it on the intake where you can see the gap from the driver seat and crank the car. If there is no spark check the connectors for the sensors and try again. Seldom is it the coil.

Jumper the fuel pump and see (listen) that is runs. Put some rags under the front fitting on the fuel rail and crack it open. If you get a good squirt of fuel then there is pressure in the system. No need to take the line off of the fuel filter. Then when was the last time the filter was changed?

The later model relay bases have a nasty habit of loosing tension on the prongs. Comes from people sticking jumpers into them.

[Brando]

Thanks for the info Hugh I'll do it your way.

Last time the fuel filter was changed? I have no clue. Probably never. And never was 250k+ miles ago...

[Brando]

Okay... wierd shizzle...

I replacd the fuel filter... because I already bought a new one before this problem occured. Before getting under the car I just attempt to start and ... fires up on the first crank. I pull onto the ramps to change the fuel filter and-- ew... red colored fuel pours out the back of the filter. Out the front it's red and black tinted.

Replace the fuel filter and make my way to the front of the car to check connections. Coil wires are secure and look good. Plug wires are good (disconnected, checked contacts, reconnected). Used Hugh's method and I'm getting spark up front. Then cracked a fuel line and cranked until I got a wet rag up front. I checked the AFS connector and it's tight and secure.

What the crap? Was it just being a jealous biatch because I drove the 914 all day yesterday?

[Brando]

Update: Now it probably won't run again.

I head out to the car again a few hours later... same ish, starts, run for a few, then dies. Cranked it over again, it stumbles then dies. Cracked the nut on the end of the fuel rail again and put a rag under it and I get a soaked rag (again). Checked for spark... still getting spark. Thinking the fuel pump is to blame, i try to jumper the connections on the relay board.

BIG mistake.

I jumpered the wrong holes. Oops, lovely smoldering plastic smell. Now I have a ground wire that goes to the DME relay that's toasted. I pulled the relay board and take a look... Wow. I think I smoked it through the whole wiring loom. Do I win the DAO award this year?

[onZedge]

Is the rotor loose?

[Razorback1980]

That hurts....what will you need to fix it? I guess that's a good lesson for us all...even a jumper wire needs an inline fuse.

[Brando]

Well, appears that ground can be pulled from any ground source.

Talked it over with my mechanic and he says "That's not too terribly bad... sounds like the AFS."

Anyone local have a late 88+ AFS I can borrow for testing? After I run a new ground line... of course.

[Brando]

O-Kay, time for an update.

Got ahold of the latest factory manuals from Porsche. Wow, these things are WAY better than the older ones on PDF I had to work with.

Anyhow... my connections in the relay/fusebox are still good. Amazing, I could have swore I smoked it bad but it's still useable. Followed the procedure for testing the AFS. Voltage and resistance is good and within specs per workshop manual. Checked the DME and it's getting voltage and such. Next stop was testing the fuel pump. Jumper connections 30 and 87(b). Wait... there's no buzzing, humming or any such sounds from the fuel pump. Hmm... Crack the nut on the front of the fuel rail to let a drop or two out, jumper again and there's nothing. No steady stream, no drops... nada. Jump to the back of the car and I'm getting voltage at the connectors for the fuel pump.

Should have a new fuel pump tomorrow afternoon. Now I get to see how to replace it. I hope it's not an in-tank pump.

[ae1969]

Swapping the fuel pump will be one of the easiest thing you do............Well assuming things are not too corroded...

[earlr85944]

Hey Brando, when replacing the fuel pump I have had success by draining the tank and removing the in tank filter (it just unscrews from the outside once you have the hose off from the tank to the pump), check the screen for any holes\clogs cleaning it and then flushing out the tank with water then compressed air(youll be suprised the gunk that accumulates after 20 years or 200K miles) if you dont have air the gas tank will actually drain good enough WITH THE IN TANK FILTER REMOVED, and rags to clear out the last bit of crap on the tank floor after flushing with your garden hose to allow a refill with fresh fuel , clean screen, and new pump. The above can also be done as a PM procedure to avoid any problems.

BTW, theres the in tank screen, fuel pump inlet screen, fuel filter, then the injectors have an inlet side screen also. Found this out the hard way when my in tank screen had a hole in it and made idling and sometimes starting difficult because of dirt clogging things intermittently.

[Zero10]

You checked for power at the pump, yet you do not know if it's an in-tank pump?

Did you check it at the terminals on the pump itself? If so, then you could have a bad fuel pump, otherwise it could just be dirty/corroded contacts. There are rubber boots on the terminals, but they frequently come loose/crumble.

[SoCal Driver]

Originally posted by Brando
O-Kay, time for an update.

Got ahold of the latest factory manuals from Porsche. Wow, these things are WAY better than the older ones on PDF I had to work with.

Cool. Now I can borrow them and fill in the pages missing from the PDF's!

By the way the printed ones are the same as the scanned ones -- minus a few pages.

[Brando]

The connector that supplies 12v and ground is not directly attached to the pump. It's run a short ways near the transmission mounting bar. I disconnected there and checked for voltage, and got it.

I know where the pump is, now. It has a small covering over it, making it look as if it's inside the tank.

Originally posted by Zero10
You checked for power at the pump, yet you do not know if it's an in-tank pump?

Did you check it at the terminals on the pump itself? If so, then you could have a bad fuel pump, otherwise it could just be dirty/corroded contacts. There are rubber boots on the terminals, but they frequently come loose/crumble.

[Brando]

Yarrrgh... wish I could. I have to return these today If only I had a scanner...

Good news, maybe I can borrow them again over a weekend and drive down.

Originally posted by SoCal Driver
Cool. Now I can borrow them and fill in the pages missing from the PDF's!

By the way the printed ones are the same as the scanned ones -- minus a few pages.

[Brando]

Yay! It lives again!

Only cost freakin $180 for a new fuel pump. But hey, if this one lasts another 250k miles I've gotten my money's worth.

[earlr85944]

Congrats! Help it last, check, clean , change the intank screen. No need to drop the tank it unscrews from the outside.