Uphill fuel problems

[turtle5353]

Hey guys, I wanted to pick your brains. My new motor has been running great all summer. Well the other day it acted like it was running out of gas going up hill. Kept wanting to shut down. Never actually shut off but started missing like running out of fuel. I was just under 1/4 tank. Seemed to go away on flat ground but going up hill on a load it did it a couple times but only on long hills. Only did it couple times. Then I filled up the car and it took 13 gallon so I still had 7 gallon left in the tank. Drove couple days all good. Then yesterday took kids to get icecream and it started same thing again on long hills. And I was just around 1/4 tank or a touch below. So is there any rubber material on the sending unit that could clog the pick up?? Just wondering if it could be that or fuel filter plugging up some and when the carb fuel in bowls goes to back it starts to miss.... possibly pump cant keep up with demand and stress of sucking through clogged filter???

Fuel filter is about 1 year old , carb and motor 1 year old. Tank is about 4 years old maybe 5?? All new fuel lines from tank to pump same time as tank. Wonder if the rubber line at tank to steel line or steel line to pump is breaking down after 4 or 5 years and plugging filter???

I will probably start with the cheap easy stuff like the 2 rubber lines and filter and go from there.

Any other thoughts fellas??

Carb is quick fuel 900 cfm, braided stainless line, mechanical pump, 408 ci Cleveland stroker afd aluminum heads.

Let me know what you guys think. Has ran great up till last couple days!!

Thanks!

 

[CZ-75]

It certainly sounds like something going on with the sending unit.

 

[Mister 4x4]

How steep was the hill? :huh:

Could it just be the fuel flowing away from the sending unit pick-up on the incline?

 

[turtle5353]

How steep was the hill? :huh:

Could it just be the fuel flowing away from the sending unit pick-up on the incline?

I was thinking that too but I still had almost 7 gallon of fuel in tank. Hills weren't really steep but long.

 

[nailpounder]

fuel filter not letting in enough , fuel under a load

 

[Luke]

Had a similar issue in a 65 impala. Dirty partially blocked screen on the pick up was sucking closed under load. May be worth looking at.

 

[Luke]

Oh and I had another car with a mild sbc that sucked the rubber section of the stock fuel line flat. again under load near wide open going up hill.

 

[turtle5353]

Oh and I had another car with a mild sbc that sucked the rubber section of the stock fuel line flat. again under load near wide open going up hill.

Thanks Luke. I will try the easy stuff first. Hope I don't have to pull the sending unit, they are a pain in the ass to get to seal properly. All that stuff is less than 5 years old, but I guess gas with ethanol can eat those rubber lines up in a hurry.

 

[Luke]

Yep if the sender unit was in the top of the tank that would be easy.good plan i always start with the basic easy stuff mostly because i dont know too much more Sometimes i thing we look for more complex solutions to simple Problems Ethanol can gum up lines if there is moister about bit like with methanol. Good luck hope it not a pain to find

 

[will e]

Had you been driving the car for while when this happens? You might be getting some vapor lock. Check the routing of the lines as well.

 

[72HCODE]

could be a couple things.

clogged sender is high on the list.

The sock in the tank could of gotten a bunch of junk stuck to it.

you will need to drain the tank and pop the sender out and have a look at it.

clogged fuel filter.

could also be:

sender float could be miss reading and 1/4 of a tank might be empty or close to it.you would be able to test this drain the fuel pull the sender and have a look at it. clean the sock if needed, then reinstall the sender and fill tank with 5 gallons of fuel then go inside and look at the fuel gauge it should read about 1/4 tank, if it is reading more then you will need to drain the tank pull the sender again and bend the float arm you have to keep messing around with it till it reads right, fill and drain.

A split fuel line, i had this happen to me.. Ethanol gas eats fuel lines. My car ran great then one day the state switched over to ethanol gas suddenly the car would not start or run correctly. turned out the ethanol made the fuel lines brittle, where ever the line had a tight bend it split it was weeping fuel and causing the fuel pump to suck air and lose pressure it happened most when the tank was below 1/2

clogged fuel filter. if you have a external fuel filter this would be the first thing to check and or replace.

possible fuel pump going is another possibility.

fuel vapor system clogged is yet another possibility.

------

First inspect the external fuel filter if you have one.

Next I would inspect the sender while involves draining the tank and looking inside the tank through the sender mount to see if there is rust inside the tank. clean the sock if needed, if the tank is really bad inside then replace it. otherwise when you reassemble double check the fuel gauge reading with a 5 gallon test.

If the tank is clean and the sock clean then inspect the soft fuel lines for splits. if found replace if not then suspect the vapor or fuel pump itself.

To test the vapor system when the car starts to show the miss problem on a hill open the fuel cap and drive for a short distance to see if the problem stopped or not. if it stops then you will need to investigate the fuel vapor system or go to a 1970s fuel cap that is vented and deal with the vapor issue another time. if the vapor system isn't the problem and pulling the cap does nothing then i would replace the fuel pump.

if you did all this and still have a problem you could have a possible blockage in the hard lines, i would take a air compressor and blow out the lines, being careful to put a rag at the other end to catch fuel and debris for inspection.

 

[turtle5353]

Thanks guys. The entire fuel system is less than 5 years old. New tank, sending unit, hard lines, fuel filter, pump, and carb. The carb, pump to carb line, and filter are less than a year old. I will start with the small portion of rubber hose at tank, at pump and inline filter. Try to get to it tonight and figure something out. If that don't work I will pull the sending unit and check it. My gauge read around 1/4 tank and I filled up the car and it took 13 gallon. So I actually had a little over a quarter tank at 7 gallon when the problem first appeared. I would think that would be plenty of fuel to get by with. All sending unit was new and the problem just recently came about

 

[setrumbo]

I had a similar problem and it ended up being a defective sending unit in my 72 convertible. It acted like it was out of gas even though there was at least a gallon or 2 gallons in the tank. This happened not long after installing a new sending unit and I was headed uphill when it quit in me.

 

[MotoArts]

C'mon yinz guys. Overthinkers, all a ya.

The solution... just keep going downhill. ::shrug::

Sheeesh.

 

[turtle5353]

Well, I replaced the front rubber fuel line and filter. The old ones looked perfect but changed them anyhow. Pulled the rubber line from tank to frame and it looked fine too. I put a new hose on the tank and not 1 drop of fuel came out??? So I blew up in the tank and could barely blow into the tank even with gas cap off. So I figure the sock must of gotten clogged??? I don't know how, its all new?? So I put my air hose on the fuel line and blow up into the tank and hear POP. I think I blew the sock off the end of the pick up tube. Fuel flowed easily from the tank then. So looks like I will be pulling the tank and putting in a new pick up and sending unit. Whats the sock made of?? Could the ethanol in the fuel have caused it to deteriorate and collapse on itself??

 

[71_resurrection]

had this problem about a year and a half ago, edelbrock told me it was the accelerator pump in the carb, then I took it to the carb guy and he tuned my carb, no problems since. Maybe check your air fuel mixture. Just my 2 cents.

 

[turtle5353]

I put it all back together after blowing back through the tank and it seems to be running fine. But I will have to pull the tank......probably over winter.

Carb is a brand new quick fuel 900 cfm and the motor builder that built my engine went all over my motor and set the carb, rejetted it, new plugs, check valve settings, and put a touch more timing in it just a few weeks ago.

 

[72HCODE]

the sock is plastic and has a plastic screen on it.

you won't know what happened until you pull the sender and find the sock inside the tank.

actually you gave yourself more work now that the sock may of blown off.

if you do not have a second filter on the fuel line i would add one now.

if the sock did get clogged up with rust or dirt then you want to keep that stuff out of the carb with a second fuel somewhere on the fuel system.

 

[judge]

You can pull the sender assembly and fish out the sock a grab tool. Totally agree with 72HCODE. Get second filter on there asap. It could go in line near the tank the more surface area in the filter the better.