Hotter outdoors temps cause her to buck and cut out.

[dustyduds]

Hi all. I'm a newbie here and this is my first post. I have a 1977 Blazer with a crate 350/350, 1406 carb, A/C and (headers). Last year I replaced the headers with replacement exhaust manifolds from Auto Parts Warehouse. Runs fine during the winter, early spring and late fall. Now that it's hotter than blazes, she cuts out after just a few miles of driving with the A/C on. Last week, she cut out 6-8 times but restarted again after about a minute as long as I had my foot on the gas, even when stopped. When I was driving around the Costco parking lot, she kept lunging forward. Now I'm afraid to drive her. She's the only set of wheels I have right now. (My 2002 GMC Sierra has been in the shop for the last month)

Just FYI, I'm not mechanic but I have tools and know how to use them. I can disassemble and reassemble things but my knowledge of timing and carbs is extremely limited. I live in a rural area of southern Arizona without much access to stores, etc.

 

[eskimomann209]

https://www.gmsquarebody.com/threads/fuel-line.26152/page-2#post-502041

Maybe this?
But I think this is like the last 10 questions asked. Did you search?

 

[SquareRoot]

Where in AZ? I'm in Yuma, about as far south as you can go. It's a nice humid 110 today. I have a similar setup as you (350, 1406, etc). If you're close I could maybe help you out?

 

[shiftpro]

Did I ever totally get the thread title wrong... darn.

 

[Charlie]

 

[dustyduds]

Thanks for the welcome, Don. My first square body was a 1977 Cheyenne, a lot like yours only chocolate over cream. Bought her in '82 and the last of her is the trans in my Blazer.

Appreciate the offer, Mike; I live west of Tucson but not that far west!

Marcus, I did search and have been reading various threads for about a week now. I'm not understanding about the fuel pump. Mine isn't in the tank like all the newer trucks and as previously stated, I'm not a mechanic. The 1406 carb was installed in 2004. Being that old, would it have the "return" like talked about in the thread you referenced?

Also, my ex took her for a spin in May 2004 and came home on a tow truck. While slowly driving down a smooth dirt road, he somehow managed to split the trans case, drop the driveshaft and break the yoke. Took me several years to pay for the rebuild on my other 350 turbo. Then had to find someone to do the install. I've been slowly putting everything back together and replacing all the parts that weren't replaced when the engine blew up in 2003

Someone thought that the timing could be a little off but said there were no timing marks. I replaced the distributor cap & rotor (HEI), plugs and wires are new. Another thought was that maybe a few of the well meaning people that have helped me might not have put everything back on the carb correctly. Not sure if anything is missing.

I appreciate any and all suggestions, pics, etc.

Thanks!

 

[fussfeld]

What type of fuel pump you got?

The first question i would ask is that, is there a return line in the system? Being that it's a 77, there may not be. But, if not, they are fairly straightforward to put in.

 

[dustyduds]

Fuel pump is an Airtex from AutoZone.

 

[fussfeld]

Can you put up a pic?

 

[Arkansas_V8]

Hi all. I'm a newbie here and this is my first post. I have a 1977 Blazer with a crate 350/350, 1406 carb, A/C and (headers). Last year I replaced the headers with replacement exhaust manifolds from Auto Parts Warehouse. Runs fine during the winter, early spring and late fall. Now that it's hotter than blazes, she cuts out after just a few miles of driving with the A/C on. Last week, she cut out 6-8 times but restarted again after about a minute as long as I had my foot on the gas, even when stopped. When I was driving around the Costco parking lot, she kept lunging forward. Now I'm afraid to drive her. She's the only set of wheels I have right now. (My 2002 GMC Sierra has been in the shop for the last month)

Just FYI, I'm not mechanic but I have tools and know how to use them. I can disassemble and reassemble things but my knowledge of timing and carbs is extremely limited. I live in a rural area of southern Arizona without much access to stores, etc.

Same issue(identical) with a different vehichle. It was the fuel pump overheating.

 

[75gmck25]

My '75 K25 has a fuel return line, so they were used fairly early in the model run, depending on the engine combination.

Does your fuel pump have three lines connected? One will be a metal fitting and line, running up to the carburetor. The other two ports will have short rubber hoses that run over to the metal lines (fuel supply and return) on the frame rail. The fuel return line keeps the temp of the fuel lower because when the carburetor float closes off the fuel it allows the pump to send excess fuel back to the tank instead of just dead-heading at the pump. The returning fuel cools down as it goes back to the tank, and more (cool) fuel is then pulled up to the pump. Your tank would also need to have a 3 port sending unit.

You really need to find the correct timing marks, since fixing the timing could take care of multiple problems. The most accurate method is to use a piston stop to find TDC of #1 cylinder, while making sure the rotor is also pointing at #1 plug wire. Then install an add-on timing pointer that attaches to one of the bolts on the timing cover. If you are lucky it will then adjust enough line up with the TDC line on the balancer. If not, then scribe a TDC line on the balancer with a sharp knife. Then use white model paint or fingernail polish to mark the balancer line and the 0 mark on the pointer. I would also mark the 12 and 8 degree marks, since they are usually a good starting point for timing.

Time it to 8 degrees BTDC to start, and then experiment with moving it up to about 12, while listening carefully for detonation. I have swapped to aluminum heads, and found 15-16 degrees to work well, but with stock heads I think I would use 12 degrees.

Bruce

 

[73c20jim]

Where in AZ? I'm in Yuma, about as far south as you can go. It's a nice humid 110 today. I have a similar setup as you (350, 1406, etc). If you're close I could maybe help you out?

I'm in Tombstone.

 

[dustyduds]

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[dustyduds]

Hope the pics I put up help. The fuel pump is 2 outlet and the sending unit is a 2 also. Changing all that out isn't currently in the budget. Any other suggestions on how to keep the fuel cooler? Last time I had to drop the tank, it took 3 of us and now there is just me. Does GM or someone make fuel line that doesn't conduct heat as badly or is this a non-issue for every other vehicle on the road?

 

[CoggedBelt75]

If it runs alright in cooler weather but not so well in the summer heat, Somethings going on with the fuel heating up like everyone’s saying. Could be because of no return line, but I don’t have one and no issues in our triple digit temps. Looking at the last pic, it appears by the rub mark on the fuel line that it is making constant contact with the lower radiator hose. More than likely boiling the fuel in the line. You might try isolating the two. Or better yet, reroute the line away from the heat source altogether. Even the line feeding the pump “looks” close to the lower hose as well.