Author Topic: 1985 K10 Dual Fuel Tanks - Not Getting Fuel and carb question  (Read 267 times)

Offline Patman

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Howdy,

I recently purchased a 1985 K10. Aftermarket Crate 350, stock 700R4 mated to an NP208 with 6 lug  stock axles. Keep in mind that its a California truck. Meaning that its got ALL of the smog stuf still on it.

Here the deal,

1.  I dont seem to be getting any fuel to the carb. I can use a turkey baster to get fuel in the carb and she purrs. But once that fuels spent, shes dead. The last time I drove her,  she died a stop sign and my fuel gauge pegged all the way to the right, past empty. The fuel gauge has not moved since, regardless of which tank is selected. Ive never used a voltage meter before nor do I have one but Im getting one next weekend, assuming that Ill need it to help determine the cause.

What I know about the fuel system, the tanks and everything is new. Except the lines, they seem to be original. Even the switch in the cab is new.

2. Smog hoses. The PO replaced all of the hoses for the smog/vacuume system. They are all in really good shape. That said, I think I may have connected some things wrong and dont want to be complicating an already finiky fuel system. It may be helpful to know that I have a new quadrajet on it. Point being, I could use a diagram if anyone has one.

3. There are two diaphragms that hang off of the passanger side of the carb. The rear one came with the carb, the front one (the one that controls the primary choke/butterfly), I had to pull off of the old carb and install it on the new one. For whatever the reason, Im not connecting them properly and am not sure how to.

So thats about it. After this, Ill be able to take her on the road, and a little off-road for foraging for firewood too. :-)

Thanks for the help folks!

Offline Ronno6

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Re: 1985 K10 Dual Fuel Tanks - Not Getting Fuel and carb question
« Reply #1 on: May 09, 2018, 03:45:19 PM »
If the truck had been sitting for some time without running, the fuel pump may have become dry.
Try using your baster to squirt some gas down into the fuel pump as well as into the carb.
Once the pump gets wet it may begin to draw fuel from the tank.

It did the trick on my truck.................

Offline VileZambonie

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Offline Henry

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Re: 1985 K10 Dual Fuel Tanks - Not Getting Fuel and carb question
« Reply #3 on: May 10, 2018, 01:15:54 PM »
Hi Patman:
Issue #1: Probably the selected tank ran dry when the gauge was not working right and now the selector will not switch to the other tank. Take a look at your fusebox...I bet one fuse is blown which is for the selector valve...then you use all that tech info Vile linked for you to troubleshoot.

Issue #2 and #3: Figuring out what the correct vacuum hose connections are for your engine requires knowing exactly what model of Q-jet carb you have...there are lots of models of Q-jets and a million different vacuum connection schemes. From your description, it sounds as if you have a M4ME or M4MC carb...can you send a couple of pictures of the carb (front, pass side, and drivers side) and the carb ID number? Autozone has a pretty good collection of vacuum hose routings for GM products on their website.
Regards,
Henry

Offline Patman

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Re: 1985 K10 Dual Fuel Tanks - Not Getting Fuel and carb question
« Reply #4 on: May 11, 2018, 04:34:21 PM »
Thanks so much guys! Ill brid dog these out and let yall know where I end up.

Offline Patman

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Re: 1985 K10 Dual Fuel Tanks - Not Getting Fuel and carb question
« Reply #5 on: May 11, 2018, 10:08:25 PM »
Crap, I used to know this. Gimme a minute...

Offline 75gmck25

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  • 1975 GMC K25 Camper Special, 350/TH350/NP203
Re: 1985 K10 Dual Fuel Tanks - Not Getting Fuel and carb question
« Reply #6 on: May 18, 2018, 02:25:45 PM »
The main gas tank is the driver's side, and with no power to the solenoid it should default to that tank (unless they hooked up the lines wrong).

I would put five gallons into the driver's side tank to make sure it has fuel.  The disconnect the rubber line running to the carburetor (most folks have long ago spliced a filter into that line), and connect a longer fuel line that runs over to a gas can or other container.  Squirt your gas into the carburetor and get the truck running, and then make sure the fuel pump is actually pumping gas out into the container.  Or you could splice a brass T into that line and install a fuel pressure gauge to verify that its pumping.

If you don't get any fuel, then you may want to bypass the solenoid before you move on to buy a new fuel pump.  Working under the truck, at the solenoid, find the main metal line from the driver's side tank (should be the largest, 3/8" line), and run a fuel hose directly from that line to the 3/8" line that runs up the frame rail to the fuel pump.  This will bypass the solenoid and connect the pump directly to the driver's side tank.

The pegging of the fuel gauge is probably an open sending unit line.  Since it happens with both tanks, its probably the wire that runs from the switch to the gauge.  On some trucks that is a very long wire, and it does not run directly from the switch to the gauge. On my truck it runs from the switch, through the firewall and to the gas tank, and then back from the gas tank to the gauge.  Its run that way so that its easy to add a 2nd tank to a single tank truck.  There are a lot of places where it could be broken.

Bruce

Offline Patman

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Re: 1985 K10 Dual Fuel Tanks - Not Getting Fuel and carb question
« Reply #7 on: June 12, 2018, 04:04:04 PM »
Ive printed off the information in the link. Thats exactly what I was looking for! Thanks man!! Love this community...
« Last Edit: June 12, 2018, 06:44:51 PM by Patman »