fuel issue?

[braxton]

‘86 w/ weber carb not getting fuel

pulled the filter and emptied it, put it back on and turned it over a few times, filter fills back up but it still won’t consistently send fuel past the pump. so it’s the pump (?), but i’m reluctant to put it on that since it’s a mechanical pump. it seems like they don’t go out that often

it’s off and on. the first time it happened i just tinkered and jiggled, gave up, waited a while and then gave it one last turn. it fired right up and ran perfectly for a few days (hot days/hard miles - road trippin).

getting no gas spurting out when i remove the fuel line from the carb and turn it over

if i let it rest a while it will act like it wants to start once or twice but then just goes back to turning

starter fluid gives more of a result but it won’t stay running

about a year ago it died (felt like a fuel problem). i messed around for a while, almost gave up, and then decided to check the 15a fuse labeled “engine”, which was blown. i just switched it with the headlight fuse and it worked fine.
this makes me wonder if it’s electrical/sensors

i don’t know. has anyone had any experience trouble shooting a ‘fuel pump’ issue without actually having to change the fuel pump?

what sends the fuel into the filter but not through the pump into the carb?

sorry in advance if i don’t sound like a mechanic
i’m not
just a guy on the side of the road far away from home!


thanks

[NWMO]

braxton,

The fuel pump may not be the problem, but a new one may get you going again. I fought a similar issue and things improved with a new fuel pump, however, the real problem may be a small hole in the fuel supply line allowing the line to suck air vs fuel.

A temp solution (I’ve done this) may be to carry a small bottle of fuel you can use to fill the carb bowl with. When a pump gets puny and there’s an issue with the suction line, the bowl empties and it’s a real pain. Often, filling manually would get me going again.

Chris

[braxton]

thanks chris

i’ll give that a try. is this temp solution not similar to starter fluid? i guess pouring gas would adjust the floats and change things

again, still/always learning. my mechanical knowledge really only coming from driving hoopties my whole life and doing my own repairs


more info:

i’ve had a cheap gas cap on it for maybe 10,000 miles. one that always gasps upon opening after running a full tank (thought that was normal).

do carbureted engines need a vented gas cap to release that vacuum and not overwork the fuel pump?

also, continuing research on sensors, i found some stuff about crankshaft position sensor and airflow sensor controlling the fuel pump

does anyone know about sr5 fuel system sensors - existence/location

???


thanks again

[braxton]

*solved*

it was the pump

[NWMO]

Yes the fuel system us vented. There should not be a vacuum when you remove the cap. This happens when the vent/charcoal canister is clogged. Disconnecting the hose to the evap canister will let you know if that is your issue.

Chris

[Petros]

also, continuing research on sensors, i found some stuff about crankshaft position sensor and airflow sensor controlling the fuel pump

does anyone know about sr5 fuel system sensors - existence/location

FYI, these cars do not have crankshaft position sensor or airflow sensors. those are only on modern fuel injected cars with engine control modules (ecm) to adjust the fuel air ratio.

these Tercels just have a mechanical pump (driven by the cam shaft) that draws fuel from the tank, and pumps it to the carburetor, no sensors involved, no electrical power to drive fuel pump.

you must have been searching the internet about a fuel supply issue. make sure you are looking at the right kind of system. I have worked on many cars with EFI, and cam and crank sensors do not control the fuel supply, they let the computer know when to send the spark to the spark plug. Airflow sensors control the fuel air ratio but do not "deliver" fuel to the injectors.

be careful what you read on the internet, most of it is incorrect.

[xirdneh]

My friends Tercel sits for months at a time. Fuel pump goes bad. I suspect the Ethanol messes up the pump. I wonder if fuel stabilizer would help stop that?

[braxton]

it was sitting for a little less than three months. i drove it around for about a week and then did a few hundred miles in two days before the issue started.

not sure if/how it’s connected but imo the more info the better on this forum

[Nordical25]

The less ethanol, the better for OEM rubber gaskets. But it takes years for gaskets to worn out, not months.

The ethanol will also start to blend with all of the inpurities in your fuel system including carb, tank + fuel lines. Therefore you want to have as clean system as possible with ethanol fuel. Driving your car all the time will also keep your system as clean as possible.

[frankdavis4]

Car problems
Fuel
I bought the Tercel 4wd new in 1984, it now has 145k miles on it. A couple of year ago it started having a problem starting in cold weather. Below 50 degrees I would have to pore gas in to the carb to get to start. It would run fine after that and restart ok. It will start with the poring of gas,but will not idle and will stop when I quit poring. I have check the the vacuum connections and have replaced the diaphragm in the aux pump. About 15 years ago I replace the fuel pump. Please help.

[dlb]

Hi Frank. Your post isn't very clear -- it sounds like you're saying your car used to have a cold starting issue, but now it won't start or run at all without pouring gas down the carb. Do I have that correct?

If I have that right, my first question is when did you last replace the fuel filter? Unless its relatively new I would replace it, and if that doesn't help I would test the fuel pump following the steps in the factory service manual that is available on this site.