86 Nissan 720 sputters and dies shortly after starting

[LowFlying720]

I have an 86 Nissan 720 that has started to sputter and die shortly after being started and driven away. It has good spark on all of the cylinders and the throat of the carburetor is dry. I have put a small amount of gas down the carburetor and the engine will start and run for a very short period of time then die again. So, i'm thinking fuel starvation of some sort. If I let the truck sit for about 20 to 30 minutes after it has died it will start up normally and run just fine and I can drive it around. The last time it ran normally for the 30 minutes that it took me to get home which included climbing some steep hills.

I don't know if it has anything to do with it but this started after I had starter troubles and had to bump start a couple of times.

I've checked all the vacuum hoses (that I can see) and they look secure. None of the hoses are cracked, hard or disconnected.

Has anyone else experienced something like this or does anyone have suggestions for what to look at next?

PS: All of my paperwork says that this is an 86 but the tag inside the door says it was manufactured in July 1985 and several times I've had to ask for 85 parts to get the right parts.

[ezb57e]

Is your fuel pump running the whole time, or does it stop and then it stalls?

[LowFlying720]

When I turn on the ignition I hear a rapid clicking noise coming from the engine compartment in the vicinity of the carb. if I go back to where the fuel pump is (on the frame just ahead of the right rear wheel) I hear nothing and when I put my hand on the fuel pump I don't feel any vibration. And now when I tried to start it the engine spun up for a couple of seconds and died.

[Adverse Effects]

could be a dead pump or 1 or both of the fuel filters blocked (1 in tank other engine bay or near pump)

[LowFlying720]

I will test the pump output. There is one filter near the pump. I suppose you have to drop the tank to get the the filter inside.

[ezb57e]

When I turn on the ignition I hear a rapid clicking noise coming from the engine compartment in the vicinity of the carb. if I go back to where the fuel pump is (on the frame just ahead of the right rear wheel) I hear nothing and when I put my hand on the fuel pump I don't feel any vibration. And now when I tried to start it the engine spun up for a couple of seconds and died.

The clicking is the fuel ratio solenoid. This is normal and good.
The fuel pump will only run when the engine is running.
If the pump isn't running, filters will have nothing to do with your problem.
The ones inside the pump rarely get dirty enough to clog, but the one outside, near the pump can get bad. Probably time for that one anyway.
Try to pour some gas very carefully into the carb bowl vent tube seen in the throat of the carb. Its about 8mm in diameter. I used to use a tiny funnel, or twist a piece of paper into a small ended funnel.
There is also a sight glass on the front of the carb that will tell you if the carb is empty.
If you can get the engine to run for a minute or so, the fuel pump should be running.
If its not, check for power and ground to it while the engine is running.
If there is no power, I would suspect the fuel pump control unit, which is located on the right side kick panel, high up under the dash.

[LowFlying720]

I have a Coleman lantern funnel that is just perfect for this. I'll give it a go, and I have a new external filter that I will install.

I'll let you know how it goes.

[ezb57e]

Great.

[LowFlying720]

I am unable to locate bowl vent in the carb throat. So what I did after changing the fuel filter was to pour some gas down the carb to get it started and then it runs just fine with the pump pumping away normally. I let it run for about 10 min and shut it off. 20 min later I start it again and it runs for a minute + and dies. the float bowl sight glass is now empty.

The pump is not pumping but it is intermittent. when it's pumping its pumping adequate fuel for high demand running but when it's not it is just dead.

I opened up the fuel control module and everything in there looked good. No scorched parts, visible damage or bad solder joints.

Until I find the bowl vent and can fill the bowl for enough running time to test for power at the pump I can't really go much farther.

[ezb57e]

Make sure, but if there is no power to the pump when the engine is running, replace that pump control module. I have replaced dozens.
IMO, with all electrical components you will actually see something wrong only a small percent of the time.

[LowFlying720]

So I figured out a work around to fill the bowl. I jumpered the fuel pump at the connector for the fuel cont/shutoff relay and the pump runs and fills the bowl in seconds.

This leads me to a conclusion that the relay is the culprit because when I plug it back in and run the engine the pump does not run.

On my way to the parts store

[ezb57e]

If you mean the relay in the pump control unit I agree.

[LowFlying720]

Fuel control/shutoff module seems to have done the trick.

Thanks for the help and advice

[ezb57e]

Great. Glad it worked out.

[Brawn0417]

I have a question. I am new to asking questions about vehicles and know little about them.

Here goes. I have a Nissan (Or Datsun) Pickup. (The tabs say Datsun).

I am having issues with the vehicle not staying on. It feels like either there is an issue with the gas flow from the tank or an issue with the carb?

I have friends willing to help me relace parts. But, they want opinions on what is wrong.

[ezb57e]

See the above conversation.
You should start a new thread. This one is resolved.