'79 F/I kicking the Dr's butt !

DrDarby · Posted: Fri Mar 21, 2008 11:22 am Post subject: '79 F/I kicking the Dr's butt !

I have a '79 beetle that came to me in the fall running but leaking fuel everywhere. In October I pulled the tank, replaced all the fuel lines up front, all the filler hoses & breather tubes etc, removed the unused gas heater fuel pump and put it back together. It sat until Dec and when I went to put it in the garage it wouldn't start but I could hear the fuel pump running, I figured I had only put 1/2 gallon back in the tank it must be too low. I've now finished a complete interior and a host of other things and got back to the fuel system. I replaced all the hoses, injector seats & seals and had to replace the fuel pressure line in the tunnel from the shift inspection hole to the engine as it was rotted out at the rubber grommet.
Now it is all back together and the little bastard wont start. This car has always had a sticky double realy or something for the 20 years I've worked on it as the fuel pump runs whenever the key is on and I can hear the pump and hear gas returning to the tank.
I've been through the whole diagnostic procedure and the only thing I can see out of spec is the themp sensor on #4 head reads 4.75k ohms. The book says it should be 2.5k ohms at room temp. It is 45 degrees in the garage currently so I'm thinking maybe thet is why it is higher. WHen they fail they usually go to 0 or infinity ohms.
The car will start and run on either so I ruled out ignition issues and I can see no vacuum leaks. The battery voltage is 11.9 - 12.1 a little low but the car should start on 9.5v or better.
I was looking for some ideas before I go get my other '79 to do some comparisons. I'll find it and fix it but in the interest of time I thought I'd throw this out here.
Thanks.
_________________
Midwest Autosavers, Inc. Woodstock, IL

Randy in Maine · Posted: Fri Mar 21, 2008 11:55 am Post subject:

Are the injectors actually lighting up your noid light and what kind of fuel predssure are you seeing?

Mr. Unpopular · Posted: Fri Mar 21, 2008 1:03 pm Post subject:

My Chevy S10 would barely run after a battery change. Come to find out, the positive cable was about a quarter turn loose. I wonder if you have enough voltage for the starter to turn, but not enough voltage for the computer to run.
_________________
"In any racing engine, the nearer you are to it disintegrating, the better it's performance will be"
-Keith Duckworth, creator of the Ford/Cosworth DFV

Russ Wolfe · Posted: Fri Mar 21, 2008 1:34 pm Post subject:

Here is the temp sensor chart. If it is 45F in your garage, that sensor may not be too far off.

Image may have been reduced in size. Click image to view fullscreen.

You may have to click to enlarge.
_________________
Society is like stew. If you don't keep it stirred up, you end up with a lot of scum on the top!--Edward Abbey

Gary: OK. Ima poop.

DrDarby · Posted: Fri Mar 21, 2008 4:27 pm Post subject:

Thanks the temp sensor tested fine when I warmed up the garage.
No now I'm not getting voltage to the injectors, last night I was getting a weak flicker with a test light, now nothing with an LED so I'm off to check the double relay when I'm done shoveling this @%$@#^%# snow again.
_________________
Midwest Autosavers, Inc. Woodstock, IL

Randy in Maine · Posted: Fri Mar 21, 2008 4:56 pm Post subject:

Got dwell?

DrDarby · Posted: Fri Mar 21, 2008 8:03 pm Post subject:

zoti · Posted: Fri Mar 21, 2008 9:02 pm Post subject:

zoti · Posted: Fri Mar 21, 2008 9:09 pm Post subject:

I just checked and the brown wire goes to pin #85 on the double relay.

DrDarby · Posted: Fri Mar 21, 2008 9:20 pm Post subject:

Thanks, whoever wired the has pin #85 grounded to the ecu chassis, same place I ran the brown wire to so it it OK.

I'll report back maybe Sunday when I have more time to play with it.
_________________
Midwest Autosavers, Inc. Woodstock, IL

zoti · Posted: Sat Mar 22, 2008 7:12 pm Post subject:

Any updates?

DrDarby · Posted: Sat Mar 22, 2008 8:43 pm Post subject:

I won't get back at it until Monday I had to finish a couple other jobs.
_________________
Midwest Autosavers, Inc. Woodstock, IL

zoti · Posted: Sat Mar 22, 2008 8:57 pm Post subject:

DrDarby · Posted: Mon Mar 24, 2008 2:04 pm Post subject: Update

OK: Problem #1 was a corroded connector in the F/I's ignition coil sensor wire at the three pin connector under the back seat on the left side. It is a black wire. This is the wire that gets current from terminal #15.

Problem #2 was someone replaced the connectors at the duel relay at one time and has the terminal #85 wire grounded to the ECU's body. The ECU is held to a painted bracket with a strap. When I recarpeted the car the strap must lay in a different spot. What I did is connect the original brown wire that came from the (-) battery cable to the ECU's bosy as well giving it a solid ground connection at all times.

Problem #3 was the battery itself. Fully charged it only had 11.5-11.9 volts. While cranking the engine I was only getting 8.6 volts to the coil. The battery must have a bad cell and when boosted is loosing voltage internally so the car still wasn't getting enough voltage. I swapped a known good battery out of another car this afternoon after not touching the '79 all weekend and it fired 1st turn of the key and runs flawlessly.

Operation a complete, thanks for your input.
_________________
Midwest Autosavers, Inc. Woodstock, IL


Hello! Log in or Register \| Help \| Donate \| Buy Shirts	See all banner ads \| Advertise on TheSamba.com

Forum Index -> Beetle - Late Model/Super - 1968-up		Share:
		Print View

	Forum Index -> Beetle - Late Model/Super - 1968-up	All times are Mountain Standard Time/Pacific Daylight Savings Time
Page 1 of 1