AJones 78

I picked up this US '78 5 speed at a charity auction a few months ago. It has a fairly well documented 70K miles, but was parked somewhere around the turn of the century.

Thanks to the knowledge and experiences you all have shared on this forum, and some luck, I was able to get it running decently. A lot left to do, but there are a couple of issues that I'm trying to address now:

1) the fuel gauge alternates between sitting on E, twitchy rapidly from E to F, reading correctly, and reading correctly then slowly decreasing a full 1/4 to 1/2 tank on acceleration. I've pulled and cleaned the crud from the sender unit, and cleaned electrical contacts at the sender. Any ideas what could be causing this? I've read of a vacuum in the tank can cause the twitching needle, but I don't see any other signs of it (no tank deformity, no air rushing in when cap opened, no blocked vents that I see).

2) There is an occasional bucking or hesitation on light acceleration, most noticeable from idle, and at slow speeds (1st, 2nd and reverse). It also can be barely felt at highway speeds when feathering the accelerator. It accelerates great at WOT at any speed. Fuel pressures were fine last I checked. Any suggestions where to look?

This is my second attempt at getting this posted, so hopefully it's not duplicative...

Thanks,
Andrew

hlee96

Wow! This is the same as my '78 petrol cork 5 spd, except that yours is a 1000% better in condition. Sorry not much help here but the bucking issues may be ignition cap/rotor/wires to the CIS injectors just needing some cleaning with a tank of gas with techron, then run the crap out of it.

Welcome and enjoy the best color combo ever (I may be bias).

Hoi

Jadz928

^^^
Although that's not horrible advice (that's one way to do it, Hoi )
Along those lines check the condition of the ignition 'green wire' from ign box to distributor.
For fuel (and owning a CIS Bosch K-Jet car), get a pressure gauge. See where you are wrt spec. Most often it's out of spec.
So yeah, change oil, changes plugs and wires (and green wire if needed), then baseline pressure test with gauge.

Re fuel gauge, try wiggling left side wire connector under dash gauge, the 12 pin piece of sh@* connector that sucks.
Playing with this may help identify the problem.

The Forgotten On

I had an issue where it was the wire being finicky behind the dash inside of the plug (everything connected correctly and clean) that caused my fuel gauge not to work.

I played with it until it worked again and hasn't caused me any grief since.

AJones 78

Thanks guys. I should have mentioned that I've done a lot of work already on the fuel system - new pumps, filter, new MB injectors, rebuilt WUR. Also, new distributor cap, green wire, plug wires. Also did the Techron, and have been enjoying some nice drives at or above highway speed! It's come a long way from years of sleeping, but just can't quite get it running perfectly. I've had problems with the throttle plate sticking (before cleaning and lube), and I wonder if it's still doing it intermittently.

I'll look at the dash gauge wire. I was hoping to avoid pulling the pod!

Kiwi'79

G'day Andrew and Welcome!!!

Great looking machine!!

I cannot help with your "miss" sorry.

As for the fuel gauge I had a similar problem, as well as my tachometer needle having a mind of its own, I have not had a problem with either since I thoroughly cleaned all the GROUNDS, including the ground "cluster" atop the CE panel, and the "plug" above the battery box (attached photos, for reference), not even sure if this plug has anything to do with the fuel gauge, one of the "gurus" will tell us. If I had the time I would have cleaned one at a time to find the "problem child" anyway, end result is all my gauges work as they should now.

Make DEOXIT your friend


Above battery box, under carpet, two plugs.


Grounds atop CE panel prior to cleaning (yes I loosened the bolt).


Cleaned

AirtekHVAC

Rey nice car. I did not see where you changed the rubber fuel lines....if you haven't, you should.....

Grounds are a definite culprit. Could be a bad in tank sender.

Wisconsin Joe

Why? It's a pretty straightforward job.

Dwayne has a great writeup on it.

The description of the gauge sounds very typical for bad connections in the pod. Maybe the plugs (3 of them into the cluster), maybe the actual connections at the gauge.

As was noted about the grounds, cleaning up the connections in the pod will help, perhaps with more than just the fuel gauge.

And DeOxit is a very good friend to have for this.

Jadz928

78 gauge cluster has only 2 connectors, right and left (no center), and both can by easily reached without removing the pod.

Since you've done the fuel system (to include a rebuilt WUR), what are your cold & hot control pressures?

AJones 78

Thanks for all of the responses. I've only been able to sneak away to the car for a few minutes today, but did see this:

This is in the spare tire well, as described by Kiwi. The female side of the smaller connector is no where to be seen, and the larger one doesn't look too good on the outside (though it's not corroded). I had thought that I cleaned all of the grounds early on in the process, but seeing this connector tells me that I may have either missed some or put them off to another day. I'll make sure to visit all of them again.

I don't have the exact numbers with me, but the cold pressure reading was in the high 20s (ambient temperature was around 60), and the warm reading was 45 as I recall . The first time I measured I had a crazy high cold pressure reading, something like 55. I might not have tested it correctly, but given that I couldn't get it to run more than a few seconds at that point, I thought it made sense to begin R&Ring the fuel system.

Jadz928

The lone 4-pin is used to connect to an Auto trans, so no worries there.
The other connector is speedo sensor and reverse light switch.

Pressures sound approx okay.

jpitman2

As above, get some Deoxit and touch up every electrical connector you come across. Also do the fuse ends and the parts they seat into - I burnt out 2 fuel pump relays because of a poor fuse connection before I found it.
Re the pod - I did an R&R on mine, and when tested on reassembly, when I turned the side lights on I got full scale fuel gauge. Advice from here - the blades in the connector hoods that contact the copper traces on the instrument panel mylar are quite soft, and even probing them with a multimeter probe can bend them out of contact; I had cleaned them with a fine emery board. If they are at all suspect, they need their tension improved with something like a dental pick to bend them. I had lost ground connection, and the dash lights were grounding out through the fuel gauge.
jp 83 Euro S AT 57k CIS

Wisconsin Joe

I wouldn't use anything abrasive on those contacts. They are way too soft and too thin.

DeOxit on a cotton swab does wonders.

If more is needed, a pink pencil eraser helps (not an abrasive white ink eraser).

The Deputy

Great looking car, looking forward to more pictures. Looks like you have the original radio, which goes for big money, $20../$30.00 dollars any day of the week...but I'll give you $40.00 to eliminate you going through all of the bother listing it.

Don't thank me...it's just the way I roll.

Brian.

AJones 78

Hey thanks. I was planning to replace it with something equally classy and understated, like this



Here are a few more pictures