'68 GMC Repairs

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Droff

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I've got a '68 3/4 ton GMC that I'd like to get worked on, I've got some engine and fuel system issues that are causing me some problems. I don't know of a garage that I can say I completely trust so thought I'd ask for some suggestions. The truck has a 350 in it with an Edelbrock carb, auto transmission, fuel tank in the cab.

My problems started when I started working on it.......
I had fuel leaking from the carb and decided I'd rebuild it (my first foray into carb work). I also decided to get the tank cleaned since there was rust in it so I got the tank cleaned and then coated it myself with a POR15 kit. Installed the tank and carb and the truck wouldn't start. Pulled the carb and went through it again, everything looked to be put back together correctly. Installed it again and still no start, just cranking. I now have a couple issues that have popped up. My tank leaked into the cab and through the mounting hole tabs. I'm guessing when I re-installed the tank, it wasn't as sealed as I thought and the seam seperated enough for it to leak. It leaked at every place there was a mounting tab.

Also, I have now had fuel get into the engine block and down into the oil pan. I can see it and smell it. Since I had an oil pan leak, all the extra fuel in there has forced more oil out and onto the driveway, so more bonus for me. My best guess is possibly the fuel pump, which is mechanical. I plan on ordering a new tank as well.

Since I have a couple things going on and not real sure on troubleshooting, I thought I'd opt to pay someone to get the truck running, it'll get done sooner. Since this is an older 'classic' truck, I'd prefer someone that likes to work on those types of vehicles, whether a business or in their garage. I don't have to have it done quickly, just done and done right. I really like older vehicles, I just seem to know enough to get myself in trouble at times.

I figure I need fuel system work as well having the oil pan pulled and gaskets replaced, likely even the rear main seal. Could possibly have engine issues with the fuel getting in there as well. Too many things for me to attack with much confidence. I'm in the Choctaw area.

Thanks.
 

MR.T.

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If you are getting fuel to the carb, which it sounds like to me that you are,
Are you getting spark?
There are in line spark testers, or pull a spark plug wire & put a spark plug on it & ground it to the exhaust manifold & see if it sparks when you crank it.
 
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Dumping a lot of gas in the oil means its flooding.. Its been ages since ive rebuilt ANY carb... And got lucky even then.. Bo is right... rusty or not . move tank out of cab. Cap the mechanical pump and go electric . if you are getting gas into the oil, then that pump is working though .
 
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I can come to you sometime when it is warmer and get it started.

Like you stated you do need to get a new tank and get it in there and run some new fuel line.
That you can do and save some coin on labor for someone else to do it.
I have lots of AFB and Edelbrock parts and have messed with those for 37 years.

Pretty simple.
The fuel in the oil pan will not hurt anything. It will just flush the old crud out of the pan.

I have had engines get a failed fuel pump and fill the crankcase with gasoline and had it pouring out of the dipstick hole.
Never hurt anything.
But within a few days that stuff was removed and good oil put in.
Use VR1 Valvoline in that old engine or Rotella T4. That flat tappet engine needs more ZDDP than your off the shelf walmart brand oil.


I am working on it @Snattlerake
 

Droff

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Thanks fellas.

Time and weather as well on my end, the truck is outside, no garage room to work on it. It's not the original engine, not sure on age, but I think it can be considered 'older', it's had a rebuild at some point.
 

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