Easy Project Gone Very Wrong

Reply Subscribe

Thread Tools

Search this Thread

Apr 26, 2014 | 08:00 PM

#16

fmc400

MSEE

Joined: Apr 2004

Posts: 10,386

Likes: 35

From: Austin, TX

Quote:

Originally Posted by phboyer

I have continuity on both of the posts and nuts on the back of gas gauge when I ground the other side. Doesn't that mean I am getting power to the gauge?

I'm having a little trouble following what you're saying. Continuity is something between two conductors; if you're trying to vet the continuity of the gauge winding itself, you'd actually want to measure the resistance. Continuity is a yes/no test.

Quote:

Originally Posted by phboyer

The plastic that surrounds one of the posts broke when I took it off when changing out the instrument cover back. It was working fine before that.

Breaking the plastic brace is a common mistake when removing the two small nuts on the back of the gauge. The posts are not strong enough to stay put while the nut is unscrewed - the correct procedure is to hold the posts steady with a pair of pliers while gently working the nut loose. Soldered to each post on the inside of the gauge is a very thin gauge piece of mag wire - you don't want the posts spinning too much.

Regardless of what happened and what the gauge is or is not doing, carry out the test described in Mike's post. This is a very common troubleshooting technique that will pinpoint where the problem is. That's why I suggested searching, as that procedure gets pulled up almost daily. Mike was kind enough to put it here too. This will tell you if the problem is toward the gauge or toward the sending unit. Since you reported that the issue didn't occur until you changed the cluster, I imagine you will find the needle does NOT peg full when carrying out the test procedure. If that's the case, there are a handful of possible causes, and we'll go from there.

May 17, 2014 | 06:16 AM

#17

hermancm

Tuned

Joined: Apr 2012

Posts: 253

Likes: 0

From: Winter, WI

Quote:

Originally Posted by NumberDummy

1975/79 F100/350 - 1975/80 Econoline - 1978/79 Bronco.

The factory installed instrument cluster backs were made of a composition material that can TURN TO DUST before your very eyes!

1981: FoMoCo came out with hard plastic cluster backs for Econolines that were also the service part replacements for these POS composition cluster backs.

E1PZ-10848-A .. Hard Plastic Cluster Back-Use with Oil & Amp Gauges / Obsolete

1975/79 F100/350 - 1975/91 Econoline - 1978/79 Bronco.
------------------------------------------------------------------
E1PZ-10848-B .. Hard Plastic Cluster Back-Use with Oil & Amp Warning Lamps / Obsolete

1975/79 F100/350 - 1975/86 Econoline - 1978/79 Bronco.

Several years ago, Carpenter bought all of FoMoCo's remaining inventory of these cluster backs. So they're NOS, not repro's.

Hey there NumberDummy, glad to see your still here! Thats exactly what you told me about my failing instrument shell last year and you were spot on! bit I haven't bouGhT one yet as mine id still hangin together but I'll have to do it eventually.

May 17, 2014 | 08:57 AM

#18

77&79F250

Moderator & parts slinger

Joined: Feb 2007

Posts: 50,260

Likes: 5,819

From: S/W Missouri, Polk county

Quote:

Originally Posted by phboyer

I don't really care about the oil pressure

You will when your motor blows up and you had no warning, cause you "don't really care about oil pressure".

Oil pressure and eng temp are the two most important gauges to have IMO.

Sound like a cluster backing issue and the boys have you line out on troubleshooting, so stick with it. But get the oil pressure gauge working also.

It could be a sending unit or a wiring/gauge problem since you are working in that area, I'd bet.

Aftermarket oil press and temp gauges are easy to install and more reliable anyway.