Fuel Fuel issue with carb and electric pump

HylanderUS

New Member
Jun 5, 2021
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0
1
44
Austin, TX
I have an 85 that started life as a 4-cyl but now has a 302 in it. The 302 is carbed, but because of some cam replacement (I was told...) the previous owner swapped to an electric fuel pump. This is a "Mr. Gasket" external pump that sits on the frame right in front of the fuel tank. I bought it like this (with lots of other weird mods), and am trying to get it to run.
It's currently either not starting at all, or backfiring dramatically through the carb. I've bought one of those see-through fuel filters and put it right in front of the carb to see what's going on. Here's what I did:

1. I turned the ingition to second position, and the fuel pump starts priming right away...but then never stops priming
2. Looking at the see-through filter, I see that it's bone dry.
3. I drop the tank and look inside, looks pretty clean (and full enough, ~4g of fresh fuel in there). Fuel level sending gauge works (the pump is wired to that, btw). In-line filter into the pump is clear, line is clear.
4. I put the tank back in, reconnect everthing except the line going out of the fuel pump. Put that in a bucket instead and set ignition to 2, fuel flows into bucket. So, the pump is running when it should be at least...
5. I put everything back together as it was, and try to start the engine again
6. The filter fills up with fuel, the engine starts blubbering. The fuel level drops in the filter, engine backfires and dies
7. Go to prime/start again, the level in the fuel filter doesn't move at all, it's like 1/4 full
8. I connect a fuel pressure gauge instead of the filter. With pump of I'm at 0 psi (duh...) and while priming I'm somewhere around 4psi

Any idea what's going on here? I haven't measured voltage at the pump yet, but it's almost like the pump isn't pumping hard enough, or sometimes fails to pump? It sounds like it's running continuously, but it's not producing the 5-7psi the holley 4b carb needs. It sounds kinda lound and "gurgling", though could be that's just what this pump sounds like, I never heard the car run...
Or is there something wrong with the carb setup? I bought a new (refurbished) one from Holley and left it unfiddled with at factory settings (just to rule that out) but maybe I'm missing somethin on that side as well (haven't worked with carbs much)
 
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General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
20,686
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203
polk county florida
You likely need to sort that fuel system out, or should I say finish sorting out.
I think it is a chance to update, but first, where is the fuel pump located?
Second, can you see fuel come out the squirters on the carb when you pump the throttle?
 

HylanderUS

New Member
Jun 5, 2021
8
0
1
44
Austin, TX
The fuel pump is outside of the tank, right in front of it mounted to a frame rail.
Not seeing fuel coming out of the squirters when pump the throttle, no.
 

General karthief

wonder how much it would cost to ship you a pair
Mod Dude
Aug 25, 2016
20,686
7,104
203
polk county florida
Ok, about the fuel pump and it's location, I'm selecting the fuel pump based on what is written, lack of fuel in filter and no squirt from the squirters, consider a 'in tank' fuel pump for longevity, it's a little more money and a little more time but it will last longer, most times (?) quieter, also a good time to consider inertia switch for safety.
Or you can swap the external pump with a new one, pay attention to where it's mounted and you'll be good for awhile.
 

HylanderUS

New Member
Jun 5, 2021
8
0
1
44
Austin, TX
Alright, I put in a new Holley Blue (omg is that thing loud...), and ran a whole new fuel line (nylon braided hose w/ AN connectors) to the front. I'm getting ~7psi before the carb now, right after the (newly added) regulator, so the pressure is now where it should be, great. It still won't start, but that's probably another issue to sort out. However, shouldn't the pump stop priming after the pressure has built up? Maybe I'm just now noticing now because it's so loud, but it's not supposed to just keep running/priming forever, right?
I do need to redo the wiring there still (the power to the pump is hooked up to the fuel sending unit, that can't be good...), but I thought whatever makes the pump stop priming would be some internal pressure switch. Is that not the case?
 

HylanderUS

New Member
Jun 5, 2021
8
0
1
44
Austin, TX
Yeah I installed the rubber thing that came with it, might be a bit thin...
However, it runs now! Kinda... I took the valve covers off and hand-cranked the engine to confirm my firing order, and re-watching that video I noticed that the distributor was off 180deg, duh...