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CarburetorsCarb discussion and questions. Upgrading your Third Gen's carburetor, swapping TBI to carburetor, or TPI to carburetor? Need LG4 or H.O. info? Post it here.
Last year this time I put a rebuilt 350 into my third gen with a holly 600 carb. everything was fine until it died at an intersection last summer and wouldn't start again for quite a while. eventually i got it running again and drove home without incident.
since then though, that problem has grown to the point where I can't trust it to get me even a mile away from home, because it will repeatedly die and not start. Also, since the weather has gotten colder, it's almost impossible to get it to run in the first place. from a cold start it will crank endlessly, run for about 2-3 seconds, then die. eventually it will get warm enough to run, just to die again after running for a few minutes.
I've replaced the coil and module, and ive replaced the holly 600 with an identical, rebuilt one. The carb and choke is working as intended, as far as i can tell.
I'm running this fuel pressure regulator https://www.summitracing.com/parts/sum-220058 but i cant rule out that the pressure is too high since the gauge that goes with it doesn't seem to work, though i do have the screw backed almost all the way out, which is what i understand to be 'low'
this has gotten to the point where I'm considering selling the car since I can't use it at all. please help.
Did you check the timing ? If it won't start I'd start there, then make sure getting fuel, then spark. Bite the bullet and take it to a pro, could be something small and easy to fix. If it's something fatal, then cut your losses.
Are you sure the gauge isn't working? It almost sounds like you have a fuel pressure issue. It may be close to zero fuel pressure at the regulator.
You need to tell us more about the car: In pump electric fuel pump or mechanical pump on the side of the motor? What distributor did you use in the new engine? Stock fuel lines? Return line hooked up to the regulator?
Leave the "timing" alone, unless the hold-down bolt is loose. It doesn't just up and change all on its own out of the blue. If it ran OK before this started, then all you will accomplish by messing with it, is ANOTHER bug you'll have to fix, once you get the REAL problem sorted out.
Sounds like a fuel delivery problem to me.
I wouldn't mess around with a gauge as the first attempt, myself. Not because it's the wrong thing to do, like messing with the timing would be; it's definitely a step in the right direction; but rather, because it's WAY MORE work and expense than is necessary for troubleshooting this situation.
Instead, when it's enjoying its condition, just take out one of the lower fuel bowl screws, and see how much fuel comes out. If about 3 - 4 floz comes out, then the carb is getting fuel, and you don't have a fuel problem. If ALOT less than that comes out, ... the carb has no fuel in it, and you need to be examining your fuel system closely.
Remember, carbs don't work off of fuel PRESSURE; all they care about, is fuel VOLUME. 2 VERY DIFFERENT things: alot like the difference between an air hose with 100 psi in it, and the wind at .05 psi or whatever. In theory, if the fuel system could keep the carb's bowls full at .001 psi, then .001 psi is all you need. Keep the bowls full is the be-all end-all. If the bowls are full, then your fuel delivery is OK enough for it to start, and the problem lies elsewhere. If the bowls are empty, then you know where to start looking.
In reality though, 3 - 4 psi AT ALL TIMES should be enough for it to "work" well enough to run just fine. 5 or so is considered about "ideal" for a Holley carb.
[QUOTE=sofakingdom;6107685]Leave the "timing" alone, unless the hold-down bolt is loose. It doesn't just up and change all on its own out of the blue. If it ran OK before this started, then all you will accomplish by messing with it, is ANOTHER bug you'll have to fix, once you get the REAL problem sorted out.
Isnt the module inside the dist? youd have to pull the cap to replace it, therefore (at best) stuffing ever so slightly with the timing.
Id be looking at the following
1. Distributor Rotor - $5 and an 2 minute job.
2. Timing, but youre going to need to get it to run for a few mins to do that - move onto 3
3. Fuel Delivery - could be some solidifying in the pumpsock, the pump itself or the filters. To me it sounds like you arent pulling enough fuel. Not knowing the year of the car, i cant really comment but Sofa is probably on the money with the most likely cause as a fuel delivery issue.
its an 89 that originally came with a 305 tbi. fuel pump in tank.
i was under the impression that fuel pumps simply went out and didnt gradually decline. ive considered the possibility of their being something wrong that way though, and will get to it soon because i plan to drop the axle. ill probably replace the filter, pump and sending unit
right now im having a hard time justifying going out in a cold garage to do that much work on a car i cant get to run.
this experience has made me hate carbs, i just want a car that runs...
PS ill try what sofaking said when im in the spirit.
Pulling the dist cap DOES NOT affect the "timing", unless the hold-down bolt is REALLY loose. No need to worry about that. No need to mess with it. No need to add another layer of risk and confusion and extra work. Change the rotor and module, sure; mess with the "timing", no.
Fuel pumps do indeed sort of peter out gradually sometimes. Furthermore, other weird things can happen to that system; one somewhat common one being, there's a short piece of rubber or plastic hose inside the tank that connects the pump itself to the outlet fitting on top of the tank, and if that splits or otherwise develops a leak, the pump will be unable to generate pressure even though it itself works.
If in fact you have the regulator set too low, that could be the problem right there. It might not be letting any fuel through. Again, check the level in the carb to find out.
Glad to hear you zeroed in on the problem without disturbing anything else; sorry to hear it might be ... that one.
Make sure though, that the problem isn't something about the regulator or filter or some such, before doing all that work, and it still having the issue. Change the filter. Disconnect the input to the regulator and see what the pump is delivering to it.
As always, do some simple troubleshooting first, before "assuming" something and diving in and doing vast unnecessary work.
[QUOTE=sofakingdom;6107900] there's a short piece of rubber or plastic hose inside the tank that connects the pump itself to the outlet fitting on top of the tank, and if that splits or otherwise develops a leak, the pump will be unable to generate pressure even though it itself works.
01-25-2017, 08:53 PM
