85 720 stalling

[jakebson]

Been driving my truck daily since I got it running a little over a month ago. A few times since then when it has less than 1/4 tank of gas it stalls out and isn't getting fuel.

It has a new inline fuel filter and a new filter in the pump. This happened the first time with Quantum Fuel Systems replacement pump. I installed the original OEM pump (that I initially thought was bad) and it stalled out again. It will restart after sitting for a few minutes and drive a bit before stalling again. I replaced the fuel pump relay and reconnected the wires they had jumped. I am going to pull it out tomorrow and see if the new one has gone bad also. I think my ignition switch may be going out because it will occasionally have trouble starting. I had a separate thread about that. Could that have any effect on it while it's running? Sorry if that is a stupid question.

 

Jake

[Thomas Perkins]

Take your ignition switch out with little hard to get to screw and clean terminals with sand paper.Just did mine not long ago.It did not effect mine when running.What I used to get the little phillips head screw off and on.

Edited December 18, 2024 by Thomas Perkins

[Xiao_Hu]

Might as well take the entire tail off the switch and use a bit of deoxit on the inside contacts as well. 

[Thomas Perkins]

I did clean the connectors in the blue connector as you see.

Edited December 18, 2024 by Thomas Perkins

[jakebson]

33 minutes ago, Thomas Perkins said:

Take your ignition switch out with little hard to get to screw and clean terminals with sand paper.Just did mine not long ago.It did not effect mine when running.What I used to get the little phillips head screw off and on.

 

I'll take that out and clean it tomorrow. Wasn't hopeful that would be a fix to the stalling issue, but it needs to be done either way. Thanks for the pointer on the tool.

[Xiao_Hu]

25 minutes ago, Thomas Perkins said:

I did clean the connectors in the blue connector as you see.

My apologies not all of your images came through on my device the first time. It must have taken time for them to get cashed. 

[datzenmike]

1 hour ago, jakebson said:

I think my ignition switch may be going out because it will occasionally have trouble starting. I had a separate thread about that. Could that have any effect on it while it's running? Sorry if that is a stupid question.

 

Jake

 

Well this depends. The ignition and the fuel pump can't know when the gas tank gets to 1/4 can it??? This leaves the pump not getting fuel at the 1/4 point on the gauge. Perhaps the float sticks at 1/4 and goes no lower. The tank empties and runs out of gas?

 

Take some fuel with you and run it out. When it quits at 1/4 put enough in to get you to a gas station. Now... how much gas will fill it? If just under 16 gallons then it ran out and the sender was/is stuck. 

 

Trouble starting? Does the starter stop working when key turned? or it turns the engine but fails to fire?.....

 

 

[Thomas Perkins]

The stalling is your carb problem,clean the ground wire and see if that fixes it.There is a sellerwith a Nissan 720 fuel lump for sale,he also cleaned the ground wire,says it works,it is rusted,as is.I bought from.him,he is in Georgia, up the road from me.It is 59.99.hm.His user name on Ebay is B&B Georgia Surplus.Ships fast.Put itnin a sand blstervencloser make it look.new,we have on at work1980-1986 Nissan Datsun 720 Truck OEM Fuel Pump Assembly

 

B&B Georgia Surplus (1784)

99.2% positive feedback

 

$59.99Free shipping

Est. delivery Fri, Dec 20 - Thu, Dec 26

Estimated delivery Fri, Dec 20 - Thu, Dec 26

C⁹onditionon.Ebay

 

 

[jakebson]

4 minutes ago, datzenmike said:

 

Well this depends. The ignition and the fuel pump can't know when the gas tank gets to 1/4 can it??? This leaves the pump not getting fuel at the 1/4 point on the gauge. Perhaps the float sticks at 1/4 and goes no lower. The tank empties and runs out of gas?

 

Take some fuel with you and run it out. When it quits at 1/4 put enough in to get you to a gas station. Now... how much gas will fill it? If just under 16 gallons then it ran out and the sender was/is stuck. 

 

Trouble starting? Does the starter stop working when key turned? or it turns the engine but fails to fire?.....

 

 

 

I don't believe it is out of gas. I drained it right around "E" a week ago to make sure there was nothing in the tank and there was still well over a gallon in the tank. I thought it might have been a residual issue of the tank being gunked up from sitting so long. The gas was clean at that point. I figured the gas being low was just a coincidence, but it has happened 3 times now and they have all been when the tank was low so I mentioned it. Didn't seem probable to me, but I wanted to be thorough in the description. It will also start and drive again for a short time before dying again. Usually a minute or so.

 

 

As far as the starting issue, when the ignition is on the starter does not come on at all on occasion. After jiggling it around and trying a few times it will catch and start right up. It seems like a connection issue, but I haven't check the voltage at the starter to confirm.

 

[datzenmike]

I don't think any tank empties completely when empty. The pick up tube does not reach right to the bottom of the tank so that it doesn't pick up any sediment or water that may accumulate. I guess the fix is to keep the tank filled up.

 

 

 

 

[Crashtd420]

Is it possible the pickup tube has some holes in it below 1/4 tank?

 

I have no idea what a good way to check that is..... 

[jakebson]

I put a gallon of gas in it this morning to see if it just needed more fuel. It will start but will then stall out again the same as before. There is noise coming from the fuel pump relay now. Hard for me to describe the noise.

[datzenmike]

Buzz? The choke heater relay will do this if the alternator is nearing it's end. Put your hand on it, you should be able to tell which one is doing the buzzing.

[jakebson]

32 minutes ago, datzenmike said:

Buzz? The choke heater relay will do this if the alternator is nearing it's end. Put your hand on it, you should be able to tell which one is doing the buzzing.

 

Ok, it is the choke heater relay making the noise. I guess I'll have to start keeping an eye out for an alternator also for the future.

 

After I let it sit I went out and started it and was able to pull it off the street and into the driveway. It ran fine for about 10 minutes before I shut it off.

[jakebson]

Also I need to deal with this now. The vacuum hose was loose and I gave it a slight nudge and the plastic broke. Looks like the previous owner may have had the same issue on the other one. Going to replace that hose also.

Edited December 18, 2024 by jakebson

[Thomas Perkins]

Here is mine ,just took this picture, check your filter at the bottom,may need replacing.

[jakebson]

4 minutes ago, Thomas Perkins said:

Here is mine ,just took this picture, check your filter at the bottom,may need replacing.

 

The hose on the right of my picture, the plastic piece broke where the hose connects to the canister. The Dist Vc hose. Looks like the same thing happened on the other side at some point because it is rigged up with some sort of glue and a screw. Wondering if there is any fix because new canisters are pricey.

[datzenmike]

Superglue it.

[DwayneOxford]

The cannister isn't essential. 

[jakebson]

This is a bit embarrassing, but while checking over everything again after swapping in a few fresh vacuum lines I noticed the negative terminal was pretty loose. Put a new one and it started right up. Let it run for a bit and took it the gas station and filled it up, and it's running fine for the moment. Do you all think that may have been the root of the issue all along?

[ElliotV]

2 hours ago, jakebson said:

This is a bit embarrassing, but while checking over everything again after swapping in a few fresh vacuum lines I noticed the negative terminal was pretty loose. Put a new one and it started right up. Let it run for a bit and took it the gas station and filled it up, and it's running fine for the moment. Do you all think that may have been the root of the issue all along?

If the alternator is going bad it could be something to do with it possibly. I dont understand how that corelates to it dying at quarter tank

[jakebson]

11 hours ago, ElliotV said:

If the alternator is going bad it could be something to do with it possibly. I dont understand how that corelates to it dying at quarter tank

 

Yeah, me neither. Perhaps it's just a coincidence. I put over 12 gallons in it yesterday between the can and the pump. FSM says the tank is 13 1/4 for standard wheelbase 2wd so maybe it was lower than I thought. I'm not sure the issue is gone, guess I'll find out when the tank gets low again.

[datzenmike]

The pick-up tube does not reach all the way to the bottom of the tank so there will always be some gas left. Maybe sender sticks somewhere below 1/4 tank?

[jakebson]

27 minutes ago, datzenmike said:

The pick-up tube does not reach all the way to the bottom of the tank so there will always be some gas left. Maybe sender sticks somewhere below 1/4 tank?

 

Definitely something I am going to look at. Thanks again for all the help to you and everyone else.

 

Jake

[ElliotV]

28 minutes ago, datzenmike said:

The pick-up tube does not reach all the way to the bottom of the tank so there will always be some gas left. Maybe sender sticks somewhere below 1/4 tank?

yeah or just old sender and gauge they do lose their accuracy over time