Slant Six Forum
https://www.slantsix.org/forum/

Non-starting, fuel pump issue?
https://www.slantsix.org/forum/viewtopic.php?t=67514		 Page 1 of 1
Author:  the mothership [ Fri Nov 24, 2023 10:28 pm ]
Post subject:  Non-starting, fuel pump issue?
I'm having a non-starting issue, and I'm wondering if it's possibly maybe fuel overflowing the carb into the cylinders. Here's the chain of events:

Just went through a tune up (oil change, valve adjust, timing, cap/rotor/points, air filter, pcv). Got it running really nice, idling well. Drove it maybe 50 miles in all, felt like a hero. I DID notice a couple times I started it, it would "hesitate" - like the starter was meeting some resistance, then would sluggishly chug-chug, then fire up. Then I filled up the gas. Next morning, it wouldn't start. First, I should say, I made the mistake of parking it in the wrong spot - it was tipped ever-so-slightly to the left, meaning fuel was dribbling out the gas cap. Tried to move it, it would not catch and start up (not the same as the resistance I had before, just turning over and not starting). I checked for spark, plugs were fine.

On the to-do list was a carb rebuild, as it'd been six years or so on the last one. I noticed that gas was leaking out of the gaskets on the carb, and at the carb/manifold connection. (Incidentally discovered that the carb was barely finger-tight onto the manifold - yoiks. Tightening it did not help, btw). Removed carb, saw that there was gas in the manifold (not a deep pool, but definitely wet).

SO, I'm assuming there's an issue with the float and/or needle, possibly allowing it to overflow? Question is, why would this occur after filling the tank? I know there's some expansion of the gas, which was helping it to spurt out the filler neck - could that also push more fuel through the pump and carb, into the manifold?

Also, when I removed the carb, I had to plug the fuel line from the pump, because it just kept dribbling out. Like, a couple cups and no sign of stopping. Is it siphoning from the tank, through the pump? Is the pump bad? (It's been there for at least 23 years, though I don't think it's original).

I'm about to do the fuel line mod, but am worried I'm going to be drowning in gas if I disconnect any more lines in this current state.

Finally, if this sounds like I've got gas in the cylinders, possibly getting some hydrolock on those "hesitant" starts, what's the best course of action? Change the oil again?

Thanks to all you wizards - Jason.
Author:  MadScientistMatt [ Sat Nov 25, 2023 6:10 am ]
Post subject:  Re: Non-starting, fuel pump issue?
Probably no connection to filling up unless there was something wrong with the fuel (e.g. too much water in it, or maybe a cleaning additive when gunk was the only thing stopping leaks). It's very unlikely for a mechanical fuel pump to fail in a way that results in too much fuel pressure.
Author:  Rick Covalt [ Sat Nov 25, 2023 10:45 am ]
Post subject:  Re: Non-starting, fuel pump issue?
Quote:
Is it siphoning from the tank,
No it should not be. The tank is lower than the carburetor. Is the tank building up pressure and pushing it forward to the carb? Remove the gas cap and see if it quits running out up top?
Author:  the mothership [ Sat Nov 25, 2023 1:23 pm ]
Post subject:  Re: Non-starting, fuel pump issue?
MadScientistMatt - just a standard fill-up, no additives. I'm sure I'm due for a gas tank scrubbing, but that's for another time.

Rick - tried that, left the cap off for a while, it kept drooling. I actually siphoned about a gallon out of the tank to stop it running down the side of the truck, but the dribbling out the fuel line is still going.

Thanks for your input - any more ideas?
Author:  Rick Covalt [ Sat Nov 25, 2023 1:59 pm ]
Post subject:  Re: Non-starting, fuel pump issue?
Quote:
it kept drooling.
Sorry, but that doesn't make sense to me? What is pushing the fuel up hill?? :?
Author:  SlantSixDan [ Sat Nov 25, 2023 2:19 pm ]
Post subject:  Re: Non-starting, fuel pump issue?
Is the vehicle parked nose-down, like on a slanted driveway?
Author:  Rick Covalt [ Sat Nov 25, 2023 3:37 pm ]
Post subject:  Re: Non-starting, fuel pump issue?
Sorry I may have misunderstood. I thought you were removing the fuel line at the carb and it was leaking there? But it sounds like it may be down at the fuel pump? Yes that is possible. Especially if as Dan says about being parked down hill
Author:  SlantSixDan [ Sat Nov 25, 2023 7:04 pm ]
Post subject:  Re: Non-starting, fuel pump issue?
Quote:
I'm having a non-starting issue
On your…ummmm…2007 Toyota Camry? Well, maybe not. But it would help if you would please say whether you're working on a '60 Valiant, a '75 Duster, a '79 Volaré, a '66 P200, an '83 D100 or what.
Quote:
I started it, it would "hesitate" - like the starter was meeting some resistance, then would sluggishly chug-chug, then fire up.
This is usually an ignition-related issue. Improper timing or crossfire.
Quote:
Then I filled up the gas. Next morning, it wouldn't start.
Almost certainly unrelated.
Quote:
I made the mistake of parking it in the wrong spot - it was tipped ever-so-slightly to the left, meaning fuel was dribbling out the gas cap.
Okeh, so maybe this is a pre-'68 A-body car you're working on? I'm trying my best to guess…
Quote:
On the to-do list was a carb rebuild
Of your…Carter BBS? Holley 1920? Carter BBD? Holley 1945…?
Quote:
SO, I'm assuming
Don't do that. It usually doesn't help.
Quote:
I know there's some expansion of the gas, which was helping it to spurt out the filler neck - could that also push more fuel through the pump and carb, into the manifold?
Maybe if your tank venting is screwed up. Model/year info would help here, too.
Quote:
Also, when I removed the carb, I had to plug the fuel line from the pump, because it just kept dribbling out. Like, a couple cups and no sign of stopping. Is it siphoning from the tank, through the pump? Is the pump bad?
The pump has two one-way/check valves, called the inlet valve and the outlet valve. They both allow free flow toward the carburetor, and prevent flow the other direction. If your tank is getting pressurised because it's improperly vented, then yes, you'd see this what you describe and it would stop as soon as you remove the fuel cap.
Quote:
Finally, if this sounds like I've got gas in the cylinders, possibly getting some hydrolock on those "hesitant" starts, what's the best course of action? Change the oil again?
You're definitely going to want to change the oil again, but "some hydrolock" is like "slightly not alive" or "a bit pregnant"; that's not how this works. Hydrolock is yes or no. If yes, the engine does not move until the liquid is no longer in place or the connecting rod bends; the starter doesn't eventually get past it.
Author:  the mothership [ Mon Nov 27, 2023 10:35 pm ]
Post subject:  Re: Non-starting, fuel pump issue?
Rick, you are correct, I removed the carb and the fuel continues to leak out there, not at the fuel pump.

Dan, sorry about that, my Toyota Camry is in fact a 1967 D100, 225, with a 1BBL Carter BBS carb. Parked on a mostly level driveway, although tilted slightly forward and toward the driver's side. Thanks for your explanation of the the fuel pump's valves, I'd wondered if it was two-way or free flow one direction.

So as for the gas dribbling issue, I'm thinking it might be siphoning out of the tank. In looking at it again from a distance, the carb inlet is slightly downhill, or at least level with the filler tube of the gas tank. Earlier I siphoned about a gallon out of the tank, but it could be that the level of gas in the tank is still slightly above the carb inlet. I'll try pulling more gas out and see if that helps the dribbles.

Dan, can you elaborate on crossfire? Never heard of it, and Google wants to give me everything related to the Chrysler Crossfire. It seems unlikely the ignition timing would go out of whack so suddenly, after it had been driving well - but anything's possible I suppose?

While you're typing, can you briefly explain the tank venting - is it merely a vented cap, or is there something else in the system that could fail? I have the original service manual, but it says nothing about the venting.

Thanks again for your input, I really appreciate it.
Author:  SlantSixDan [ Tue Nov 28, 2023 11:53 am ]
Post subject:  Re: Non-starting, fuel pump issue?
Quote:
So as for the gas dribbling issue, I'm thinking it might be siphoning out of the tank.
Not likely.
Quote:
In looking at it again from a distance, the carb inlet is slightly downhill, or at least level with the filler tube of the gas tank.
If the tank were very-very full, right up to the top of the fillpipe, then maybe you could get some siphon action going. But I bet it's not.
Quote:
it could be that the level of gas in the tank is still slightly above the carb inlet.
Couldn't. No part of the tank is higher than the fillpipe.
Quote:
Dan, can you elaborate on crossfire?
It's when a spark happens in a cylinder it's not supposed to happen in. If the timing is set incorrectly or there's a problem with the cap or rotor, the spark can jump to the wrong terminal—either the one before or after the intended one—which will make a spark plug fire in a cylinder that is not ready for it. If that spark happens while that cylinder is in the middle of its compression stroke, it will fight back against the starter motor.

Or, if two spark plug leads (including the coil-to-cap lead) run parallel and close together for much of any distance, the magnetic field created by electricity travelling through an intended lead can induce a current in the nearby unintended lead—especially if an improper type of plug lead is installed, such as solid wire-core leads.
Quote:
unlikely the ignition timing would go out of whack so suddenly
I once had a rotor hit a cap contact (poorly-ground caps are a thing; read this long but worthy thread). The engine still ran, but had weird hiccups and cranking issues.
Quote:
While you're typing, can you briefly explain the tank venting - is it merely a vented cap, or is there something else in the system that could fail? I have the original service manual, but it says nothing about the venting.
The cap is not vented. The tank is vented via a small-bore steel pipe which connects near the top of the fillpipe. It is routed along the tank and then upward to a high U-turn (to minimise the likelihood of liquid fuel sloshing out) and then down to under the vehicle. Here's the diagram, with the tank vent indicated by green arrows:
Attachment:
Screen Shot 2023-11-28 at 11.48.42.jpg
Screen Shot 2023-11-28 at 11.48.42.jpg [ 91.14 KiB | Viewed 6763 times ]
Author:  the mothership [ Tue Dec 12, 2023 4:28 pm ]
Post subject:  Re: Non-starting, fuel pump issue?
Ok update - still not able to get it running due to lack of time and diagnostic skills. Since I was already rebuilding the carb I chose to do the fuel line mod also, that is all back together and looks good. Even replaced the heater core, sure will be great if it ever runs again...

Re: tank vent - Dan my truck does not have that vent line at all - no vent anything that I can see. Which seems weird...

Anyhoo, started with the easy stuff and replaced spark plugs wires, and in doing so realized that my distributor is set up 180 degrees off of any diagrams I see out there.... Still in the correct firing sequence, but whereas #1 should be in bottom right, that's where my #6 is.... Which explains why the plug wires are stretched awkwardly. Now, I haven't moved the distributor in the 20 whatever years I've been mistreating this poor truck, and generally it's run fine.

Another question about the distributor, the cap has always felt sloppy - it's clipped on with the two spring clips, but you can easily wiggle it around. Which seems bad for maintaining proper gap clearances, am i right...? This is true of any cap I've put on it. Is this a standard feature/bug?

Finally, what are your recommendations for next steps? I checked continuity on the coil-to-alternator wire, seems good. Fat sparks from the plugs. Changed to a different cap, still not starting. In fact I'm back to hesitant start - ie: seems to be pushing against some resistance when cranking. Is it possible the who-knows-how-old distributor just gave up?

Appreciate any ideas or direction, thanks guys.
Author:  Rick Covalt [ Tue Dec 12, 2023 5:53 pm ]
Post subject:  Re: Non-starting, fuel pump issue?
Quote:
Is this a standard feature/bug?
No, there is a notch in the cap and a tab on the distributor that fit together. Once they are lined up the cap should not be able to move around.
Author:  Charrlie_S [ Wed Dec 13, 2023 3:49 am ]
Post subject:  Re: Non-starting, fuel pump issue?
Quote:
I checked continuity on the coil-to-alternator wire, seems good. .
???
Author:  the mothership [ Wed Dec 13, 2023 8:24 am ]
Post subject:  Re: Non-starting, fuel pump issue?
Whoops sorry Charrlie_S, I meant coil to distributor. :roll:
Page 1 of 1 All times are UTC-07:00
Powered by phpBB® Forum Software © phpBB Limited
https://www.phpbb.com/