Jump to content

1984 Nissan/Datsun 2.4 Truck will not start. Please Help!


Recommended Posts

Hi. I had the relay plb several times, now it's worse. I can't get the fuel to flow at all. Swapped out several relays, 2 pumps, checked cleared lines. Only thing I found off was a temperature sensor below the carb. Could it be somehow cutting power to the relay? No pics at the Nissan dealership of the sensor. The new replacement both dealer and advance has a smaller diameter mount and different threads and longer sensor.  I may need a new ignition. I hate this electric crap. I hate to keep pumping money into it. I got a new relay cheap one from rock auto. It didn't work and I got an expensive one from the dealership, but scared to try it with out knowing for sure. it might blow too. I thought one of the old relays that was working intermitently would at least get something going, but i got nothing.

  • Like 1
Link to comment
  • Replies 38
  • Created
  • Last Reply

Top Posters In This Topic

Top Posters In This Topic

Give this a read. It's easy enough to jumper the pump so that it is on when the ignition is on .... and that's all you really need.

 

https://axleaddict.com/auto-repair/The-Datsun-and-Nissan-Pickup-Fuel-Pump-Relay-What-the-Haynes-Automotive-Repair-Manual-Wont-Tell-You

  • Like 2
Link to comment

Hi, Ok. Thanks for the tips with the wire diagram. Ignition seems to work. Power to pump, but pump not running. I had a fairly new one that I tried, but it must be bad too. The other time I got one and found the relay, I switched back to the old pump and kept the new for backup. I guess it's messed up from sitting a long time. I don't think the temperature sensor I found lose has anything to do with the pump system. I couldn't find another, so I soldered the wires back on to the terminals. Maybe it will work. I like this Datsun Rat Rod site. Can't wait till mine doesn't need inspection anymore. Have 1 more year to go. Does the Weber carb have any pollution control stuff on it? I'd like to go straight carb like racers use.

  • Like 1
Link to comment

I just recently moved my 521 cab to a 1986 Nissan 720 chassis and I used a 1980 Datsun 720 wiring harness, I had to jump the power wire to the 1986 fuel pump and that made it run all the time when the ignition is on which I really don't care because it has a return line so it cycles this crap fuel they sell now days, well all of a sudden my fuel pump started working intermittently, I checked the power to the pump and it had power, well the issue turned out to be the stock ground wire, if I wiggled that wire it would sometimes turn on briefly, so I added another ground wire and used the fuel filter mount bracket/clip mount screws for the new ground and I spliced into the stock ground wire with one of those vampire type clips that one uses pliers to connect them, it has worked great ever since.

Grounds are very important in these 720 wiring harnesses.

  • Like 1
Link to comment

Hi. I had the relay plb several times, now it's worse. I can't get the fuel to flow at all. Swapped out several relays, 2 pumps, checked cleared lines. Only thing I found off was a temperature sensor below the carb. Could it be somehow cutting power to the relay? No pics at the Nissan dealership of the sensor. The new replacement both dealer and advance has a smaller diameter mount and different threads and longer sensor.  I may need a new ignition. I hate this electric crap. I hate to keep pumping money into it. I got a new relay cheap one from rock auto. It didn't work and I got an expensive one from the dealership, but scared to try it with out knowing for sure. it might blow too. I thought one of the old relays that was working intermitently would at least get something going, but i got nothing.

If you are talking about oil pressure sensor under the carb on the side of the engine block then yes this could be a problem.  To keep the engine running it has to "sense" oil pressure or the pump shuts off.  This is a safety feature to save engine from no oil pressure and also in case of an accident no fuel leaking to catch fire.

Link to comment

Same problem 85 4x4. Have all good at relay plugs, pump runs when jumped so suspect wiring.

 

As King Rat mentioned manual good for toilet paper as far as fuel system concerned. Considering running new wires but no idea where to tap in.

 

Was going to make a dually decker out of it, Toyota motorhome duals bolt right on, but to get the deck to cover the outside tires would mean deck 18" wider than cab on both sides. Not so good for bushwork, so cancelled that plan.

 

Located on Vancouver Island BC and have a set of Toyota motorhome rims for sale, also some miscellaneous other parts, several heads, one transfer case, and three dashes. Spare 720 4x4 in yard, body shot, rebuildable engine, lots of hard to find small shit and one engine.

  • Like 1
Link to comment

Similar problem. Pump has been bench tested, so works. Tried jumping relay connector, no juice at pump plug. Manual useless for wiring and I don't want to be tearing up a bunch of wiring harness to trace it. Any ideas?

 

I hate electrical, at least hydraulic fluid drips out on the floor so you can find the leak.

 

I am a welder so when my electrical device is working properly there is heat, smoke and flame. Apparently this is not so good for automotive wiring.

  • Like 1
Link to comment

OK Mike will check pump ground.....tomorrow. Raining and can't get truck into garage due to no start issue.

 

I did remove the old rusty screw from the fround wire and replaced wire eye, polished pump bracket and installed new bolt, but also noticed pump bracket is rubber mounted. Maybe I should weld a bolt to the frame and use that as a ground!

  • Like 1
Link to comment
  • 2 years later...

Thread revival? '84 z24 here. Truck hasn't started since it died about 400 feet out of the driveway last week. Hadn't noticed any fuel issues before this.

I'm not hearing ANY fuel pump activity with key in ACC or ON. Located the relay box today and jumped blue to white, but still doesn't sound like the fuel pump is turning on or running at all.

 

Did a 10 minute check on the connections around the relay, fuse box, battery and fuel pump. They seem fine...

 

Going to replace the 15a fuse and test the fuel pump with an external battery. If neither of these measures gets to pump to turn on, should I suspect the fuel pump itself?

  • Like 1
Link to comment

400 ft is about how far you would get with no fuel pump running on the gas in the float chamber

 

It may be on the fuse box cover, but it's the 5th fuse over from the left side. 15 amp. With a test lamp grounded,  touch both exposed contacts the lamp should light on both if working.

 

Unplug the pump and check for power on the BROWN wire with ignition on. If power and no pump the pump is at fault. Well unless the ground is at fault. To check clip your test lamp to 12v and touch the BLACK wire. If it lights the ground is good.

  • Like 2
Link to comment

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Loading...
×
×
  • Create New...

Important Information

By using this site, you agree to our Terms of Use.