Fuel Injection Gremlin '79 Super

[abl1111]

Back from biz trip. Didn't bother to start her - removed injector with leaky hose ( will have repaired this week ).

Looking all over for leaking air hoses - none so far.

Checked fuel pressure - it's at 38psi. Bentley says approximately 35 psi - so I'm assuming I'm OK.

Will dig into the above schematic of the relay.

If anyone has a 'bad' relay - I could use it. I opened mine up and lost the tiny spring that fits on it. There are (2) springs - I lost (1).

Thanks for the continued help.

BTW - What is a smoke test ? If its what I think, I take a propane torch and point gas in direction of hose connections to see if it idle rises ?

[busdaddy]

[abl1111]

Fuel pressure. It's a single-hose connected to the gauge that I connected to fuel rail instead of the CSV. Pretty simple. It's really measuring air pressure, right ?

Is this the big black boot that connects the throttle body to the AFM ? ----> Block S-boot with a beer bottle

And, I assume that this smoke runs through the AFM as well ?

[busdaddy]

Yes, the big rubber thing with the ribs is called the S boot, AFM's don't leak unless the idle screw is removed or it's O ring is missing, but if you think it's suspect seal up the aircleaner end with duct tape, there's always a first time for every problem.

Air in the line won't change pressure readings, it all compresses until it reaches an equilibrium that the gauge reads.
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[abl1111]

I’ll try that smoke test ASAP. Gotta make one firsthand.

For the fuel gauge I made; It’s an air pressure gauge connected to a fuel line... that should read fuel pressure right ?

[busdaddy]

[abl1111]

Got injector repaired. Will install ASAP.

The fuel pressure reads between 30 and 40. There are (3) hash marks between the 30 and the 40. So, each mark is 2.5.

I'm between the 2nd and 3rd hashmark ( about 75% of the way to the 3rd hashmark...)

derivation:

30 psi plus 2.5 + 2.5 + 1.875 ( 75% of 2.5 = 1.875 ),

equals 36.8 psi

Thats my fuel pressure. Is that within acceptable parameters ?

[busdaddy]

[VW_Jimbo]

[abl1111]

No name gauge - cheapie - online from somewhere awhile ago.

Calibrated - nope.

I could buy another gauge to double check.

[VW_Jimbo]

[abl1111]

Made the smoker - will test vacuum lines hopefully, tomorrow.

Quick question on the reading the fuel pressure and my setup - I have one hose with a pressure gauge on one end and the the other end is connected to the cold start valve fuel feed.

This should read the fuel PSI correct ? I'm just turning the car over and reading the PSI, right ?

Gonna get another gauge that is rated for 60psi and under so the increments are tighter to read.

[VW_Jimbo]

[BugCaster]

I installed a port in the left bank fuel line so I can quickly check fuel pressure easily. How often do I need to? Not that much now that I got it running well but while I was going through the process of diagnosing a cold start problem it also let me keep the cold start valve working.

[abl1111]

OK - Got it figured out.

First off - bought a new pressure gauge. It read 36 psi on the nose.

The smoker detected some smoke, from behind the crankshaft pulley and a small amount from the oil filler cap ( is a gasket supposed to be on the cap )

The rag/ gas/ oil mix to create smoke did not work well. Is there a better way to make white smoke ? I don't have ping pong balls handy.

Found the Gremlin

Under the back seat, drivers side, there are several connections 'down there'. There's a BIG plastic connector where (3) large wires converge and, theres a smaller white plug where multiple wires connect <--- this is where there was a bad connection. It was NOT EASY to pin point this ! I can see how someone not as stubborn as me would miss it. The connections look fine ! But, with the key on, if you wiggle this white connector, the relay would click on and off. Again, the connections looked fine - but, once I zip-tied the two connectors together, the intermittent relay issue stopped - AND ALL FUNCTIONS THAT I WAS HAVING ISSUES WITH ---> WORKED.

So, I'm back at square one. Car starts, idles high, comes down and purrs at idle - runs at 75mph.

A few things - the idle screw on the throttle body does not raise or lower RPM. This is not normal. In the past, I was able to raise and lower the RPM's with this screw. No leaks in the air system and the fuel pressure is 36

Thoughts ?

[busdaddy]

Good news!, you are moving forward!

Maybe start by making sure there's a little slack in the throttle cable when it's at idle, next try pinching one of the big hoses to the AAR and see if the idle drops when warmed up, if it does the AAR needs work.

I hope you plan to dismantle that funky wiring connection and repair it properly, the zip tie fix may be good for diagnosis, but it's not long term.

The smoke from the crank pulley isn't uncommon, there's no seal there, the oil cap should seal fully though. Some use cheap cigars to make smoke, maybe you can come up with your own variation?
_________________
Rust NEVER sleeps and stock never goes out of style.

Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
Stop dead photo links! Post your photos to The Samba Gallery!

Слава Україні!

[abl1111]

I will take the that plug connection apart. I need to invest in a decent FI electrical connector remover - as opposed to the 'paperclips in a vice grip'.

Any ideas for a good design for this tool ?

Smoke leak at oil cap. OEM cap, so not sure if there was an o-ring gasket in there or the perfect German engineering allowed for the cap to make a perfect seal against the filler neck.

As for the inability to raise/lower idle via the idle screw - that is a weird thing. I have never had that as an issue. I'll look into it a bit more - right now, I'm glad things are back to running.

And, as usual, I hope my issue and resolution help someone else.

Lastly, and this is the weird thing - my brother who has the '78 - had the same issue as me and it was the same plug connector under the seat !!?? His car runs great...

That is so odd. My issue started only after swapping his relay.

Hmmmm.

[busdaddy]

[abl1111]

Bought that set of FI removal tools. Will redo things when I get them.

Idle Screw On Throttle Body

The fact that the idle adjustment screw on the throttle body has "0" effect on idle is really odd.

I turned the idle screw all the way out, (8 ) turns, and it had no effect ?! I could hear air rushing past the screw into the throttle body, introducing air - this should raise the idle ?!

I checked the Aux Air Valve after the car was warmed up by pulling the small black rubber hose and peaking inside to see the valve was closed, as it should be.

When I pulled the hose from the EGR going to the throttle body ( next to the idle screw ) the idle jumped up.

Throttle Cable - There is a tiny amount of slack on the throttle cable.

?

[sjbartnik]

When the idle screw has no effect that is usually indicative of a vacuum leak. The idle screw just screws into an air drilling that bypasses the throttle plate.

A classic test is to screw the idle screw all the way in. The engine should stall. If it doesn’t, air is getting in somewhere.
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