Help with a couple electrical gremlins, please.
Thread Starter
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Mountain Pass
Joined: Jun 2012
Posts: 134
Likes: 5
Help with a couple electrical gremlins, please.
1978 F-250 400/C6.
First is the fuel tank sending unit; the fuel gauge does not work. I pulled the sending unit and when it was completely inverted the gauge read full as it should. When it's installed, the gauge won't move. I tested the electrical plug and the light pulses brightly. I put dielectric grease in the plug and the needle moves just a hair from full to the left with the ignition off to the E, and its movement is very sluggish. Could this be the sending unit gone bad?
Second is in the lights. When the headlights are on, the right taillight will not work and the left brake light stays on. When the headlights are switched off, both taillights and rear marker lights turn on! I'm guessing that's a ground issue with the lights - probably a corroded socket somewhere in the system? Thanks!
First is the fuel tank sending unit; the fuel gauge does not work. I pulled the sending unit and when it was completely inverted the gauge read full as it should. When it's installed, the gauge won't move. I tested the electrical plug and the light pulses brightly. I put dielectric grease in the plug and the needle moves just a hair from full to the left with the ignition off to the E, and its movement is very sluggish. Could this be the sending unit gone bad?
Second is in the lights. When the headlights are on, the right taillight will not work and the left brake light stays on. When the headlights are switched off, both taillights and rear marker lights turn on! I'm guessing that's a ground issue with the lights - probably a corroded socket somewhere in the system? Thanks!
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
First is the fuel tank sending unit; the fuel gauge does not work. I pulled the sending unit and when it was completely inverted the gauge read full as it should. When it's installed, the gauge won't move. I tested the electrical plug and the light pulses brightly. I put dielectric grease in the plug and the needle moves just a hair from full to the left with the ignition off to the E, and its movement is very sluggish. Could this be the sending unit gone bad?
Second is in the lights. When the headlights are on, the right taillight will not work and the left brake light stays on. When the headlights are switched off, both taillights and rear marker lights turn on! I'm guessing that's a ground issue with the lights - probably a corroded socket somewhere in the system? Thanks!
Thread Starter
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Mountain Pass
Joined: Jun 2012
Posts: 134
Likes: 5
Thank you, sir! The answer to your question is yes so I'll pull the float out and check it. Thankfully it looks like LMC sells the float for $6. I wonder if I can get a float anywhere locally?
I thought it was probably a socket, I'll pull them and check them. Thankfully O'Reilly stocks them at the store down the street from my house.
I thought it was probably a socket, I'll pull them and check them. Thankfully O'Reilly stocks them at the store down the street from my house.
Thread Starter
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Mountain Pass
Joined: Jun 2012
Posts: 134
Likes: 5
Well, I didn't bother pulling the sending unit out again, just ordered a new float and gasket from LMC. My old gasket is shot and isn't sealing since fuel started leaking out. I'm waiting to pull it again when I get the parts.
I checked the front signal flashers and the tailight sockets, one is pristine. Three are seriously corroded. I'm just going to replace the three of them and go from there.
First I have to get this thing running properly, it barely runs. The previous owner's mechanic RTVd a 351C 4 bbl manifold to the block, it has no PCV valve and the "new fuel line" he told me about is nothing more than rubber vacuum hose. I'm thinking this is why there are a lot of air bubbles in the fuel filter. He bypassed the tank switch and ran a line from the side tank. I'm going to get new steel line from O'reilly and replumb the side tank. I'll redo the rear tank later. Oh, and the distributor seal needs to be replaced as it's leaking. He told me the entire engine has about 7,000 miles on a rebuild, so at least everything is fresh...
I checked the front signal flashers and the tailight sockets, one is pristine. Three are seriously corroded. I'm just going to replace the three of them and go from there.
First I have to get this thing running properly, it barely runs. The previous owner's mechanic RTVd a 351C 4 bbl manifold to the block, it has no PCV valve and the "new fuel line" he told me about is nothing more than rubber vacuum hose. I'm thinking this is why there are a lot of air bubbles in the fuel filter. He bypassed the tank switch and ran a line from the side tank. I'm going to get new steel line from O'reilly and replumb the side tank. I'll redo the rear tank later. Oh, and the distributor seal needs to be replaced as it's leaking. He told me the entire engine has about 7,000 miles on a rebuild, so at least everything is fresh...
Postmaster
Joined: Mar 2011
Posts: 2,698
Likes: 7
From: Taxachusetts
You know the Cleveland intake won't bolt to M block heads without spacers, yes?
M block deck heights are about an inch higher than the Cleveland's. Hence the gobs of RTV around the manifold. Won't work.
He told me the entire engine has about 7,000 miles on a rebuild, so at least everything is fresh...
Any way to check that? Receipts?
M block deck heights are about an inch higher than the Cleveland's. Hence the gobs of RTV around the manifold. Won't work.
He told me the entire engine has about 7,000 miles on a rebuild, so at least everything is fresh...
Any way to check that? Receipts?
Thread Starter
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Mountain Pass
Joined: Jun 2012
Posts: 134
Likes: 5
You know the Cleveland intake won't bolt to M block heads without spacers, yes?
M block deck heights are about an inch higher than the Cleveland's. Hence the gobs of RTV around the manifold. Won't work.
He told me the entire engine has about 7,000 miles on a rebuild, so at least everything is fresh...
Any way to check that? Receipts?
M block deck heights are about an inch higher than the Cleveland's. Hence the gobs of RTV around the manifold. Won't work.
He told me the entire engine has about 7,000 miles on a rebuild, so at least everything is fresh...
Any way to check that? Receipts?
The seller was truthful. I'm a federal law enforcement officer, and after he sold me the truck he friended me on facebook - I'm positive he wasn't lying about anything.
Postmaster
Joined: Mar 2011
Posts: 2,698
Likes: 7
From: Taxachusetts
Ok, good...
On the float situation - Ford dealerships still carry the old brass type ones. Unless you're opting for a "plastic" one with an aftermarket sending unit.
Good luck chasing wires and the other "little" fixes.
On the float situation - Ford dealerships still carry the old brass type ones. Unless you're opting for a "plastic" one with an aftermarket sending unit.
Good luck chasing wires and the other "little" fixes.
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Thread Starter
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Mountain Pass
Joined: Jun 2012
Posts: 134
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Ah, thanks for the heads up. The tank has an aftermarket sending unit with the plastic float, so the LMC part will hopefully work.
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Thread Starter
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Mountain Pass
Joined: Jun 2012
Posts: 134
Likes: 5
Well, my PCV valve should be here today and I can sort that out and make sure my vacuum is good. After messing with the engine for a week straight after work (mind you I'm an amateur) I finally have it idling and running perfectly. I've been dealing with fuel delivery issues, timing issues, etc. I replaced the o-ring on the distributor because it was leaking and when I re-installed it, I brought the #1 piston to TDC and installed the distributor. All the sudden the truck runs like a brand new truck, it idles, revs, etc. Obviously the previous owner's mechanic had the distributor installed a tooth off on the cam and that was why the timing was so badly off. I retimed the engine, now to adjust the carb and do a final re-timing!
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