B Lyle

Hi folks, new to the community. I recently bought a 76 and have had some fuel issues. It has the stock 350, with a holley 650 and holley street dominator intake (dual plane). I hadn't noticed any issues driving it around town, but when i get out on the highway at cruising speeds, for about 20 minutes or more, the accelerator starts to cut out, like it's wanting to stall. Sometimes if I slow down it will straighten itself out, but usually i have to pull over, shut it off and let it rest for five minutes or so, then crank it back up and it's fine for a little while, then will start again.

I took it to a local shop, and they identified a number of issues, the most pertinent being the fuel pressure (it was running at about 1-1.5 psi). I had them install a new mechanical fuel pump, the pressure is now running at 5psi. They confirmed that the flow/pressure from the tank to the pump was excellent, and shouldn't be any problems on that end.

However, they insisted that the carb/intake combo was "too powerful" for the 350 and it would never run right with those on it. They wanted to replace the carb and intake manifold with the oem parts (for about 2k bucks). I didn't think this should be the case, so I just stuck with the fuel pump replacement.

After getting it back, while it does run/idle better in general, i'm still getting the same issue when out on the open road. I'm wondering if there's actually something to their complaint about the carb and intake, or if there's another problem I should look into. I really don't want to spend that much money to put oem parts back on the car when the parts that are on there are nicer and should work in theory (as far as I'm aware). Thanks in advance for your input!

Mashman

First, I would recommend that you never set foot in that shop again.

Many people on here are running that same carb/intake combo without issue. And "too powerful"? The stock q-jet will flow up to 750 CFM, so 650 is definitely NOT to powerful.

A couple of things I would check would be the float level on the carb, and the rubber line to the fuel pump - make sure a pre-formed 'S' line is being used.

This problem should be fairly easy. And $2k to replace an intake and carb to stock?!?! They are literally trying to steal $1000 right out of your pocket, $1500 if you went with used stock components.

calwldlife

i think you should verify the ignition system before
carb and intake.
ignition module and coil and mag pickup.

TimAT

Start at the back. Make sure the fuel cap is vented or if there's a vent on the tank it's working as designed. Fuel pressure reading was a little low- I don't know what the actual idle spec is, but I'm thinking it should be around 4-5 psi. Check the rubber hoses between the tank and frame and then from the frame to the pump- replace as needed- be sure, (if they need replacement), that you use good quality hose that is rated for fuel.

diehrd

MODULE .......... would be the most likely

B Lyle

Thanks for the info guys! As a side note ( i forgot to mention earlier, but was reminded when you mentioned the module), the previous owner installed an electric fan, but wired it straight to the coil and grounded it, so it's always on. That's obviously a problem that's on my list of to-do's, but wasn't sure if it was relevant to the fuel problem.

Yeah, the shop had a good reputation around town, but all that parts replacement stuff sounded bogus to me, and way overpriced.

Thanks.

calwldlife

wow, can't be good for the electronics in the dist.

my 76 ray

Next time it happens pull over in a safe place and do some troubleshooting.

Take the air cleaner off and move the carberator linkage while looking down the throat of the carb. You should get two good streams of fuel from the jets. If you don't then you likely have a fuel problem. If you do get a good shot of fuel then it might be electrical.

If it looks like a fuel problem then look at the two rubber hoses between the fuel lines and the fuel pump. If somebody replaced the "S" shaped molded lines with standard fuel hose it may be being sucked flat causing a fuel restriction.

You can loosen the gas cap and recheck the the shot of fuel at the carb. If loosening the gas cap gives you a good shot of fuel when you move the carb linkage then you likely have a venting problem.

Good Luck

hugie82

Are you powering the fan off the coil wire or is it just a wire turning the relay on?

Also, can you floor it and get a good run out of the car or does it bog doing that too?

Mike Ward

'76s don't have coils (?)

Does your new fuel pump have three ports on it like the original or did your shop downgrade it to a two port?

AirBusPilot

HEI has an in cap coil.

B Lyle

As far as I can tell the fan is spliced into a wire coming out of the distributor ( which I assume is the primary (coil?) wire) and grounded directly to the engine block. As such it runs whenever the car is switched on.

I believe the fuel pump is a 3 port, will have to double check. It's supposed to be a refurbed oem part.

B Lyle

If i floor it when it's acting up, it sputters as if it's getting a little more gas than it was, but still stalls out ultimately.

johnt365

I would make one of my weekend projects to take that electric fan off of whatever circuit it is tapped into and give it its own dedicated circuit with a relay from either the alternator or another source of direct battery power.

To help ID your distributor, does it look like the one in this picture?

B Lyle

Yeah, the plan is to have it wired to a dedicated circuit with a temp sensor switch so that it's not continually running. I was just lower on my list of to do's, but it may move up on the list since the fuel pump didn't solve the immediate problem.

The distributor does look similar to the one in the pic, I believe it is the stock HEI or a replacement of the same model, but I'm not overly familiar with the electrical bits in these older vehicles.

B Lyle

It's also not currently running headers or true dual exhaust; something that needs to be taken care of, but I didn't think it would be causing the issue i'm h aving right now.

johnt365

I have headers. The fuel lines run right along the frame next to the drivers side header. All that heat can easily boil the fuel in the line before it gets to your fuel pump. If and when you put the headers on, I would recommend wrapping the header or insulating the fuel lines or both.

gcusmano74

Fuel filter? Or the pickup sock in the fuel tank?

B Lyle

Fuel filter seems clean (it's one of the see thru ones) and the shop confirmed the fuel tank/sock was good and the fuel flow from the tank was excellent. (The fuel tank is new, was installed just before i bought it)

AirBusPilot

I'm beginning to wonder if the carb is jetted too lean.

Car gets on the freeway, engine cools down a bit, wants more fuel (richer), and it starts to run so lean it begins to cut out.

Car sits by side of the road, heat soaks a little, and the too lean mixture works.

Just thinking out loud.