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86 4x4 720 Project


powderfinger

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Good eye Mike, I'll take a closer look at that probably this weekend. I also plan to do another compression check and compare the results to my 2wd that I know has a strong engine since the last readings were low on the 4x4. Hopefully my gauge is just off but based off how the engine feels I doubt it is that far off.

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Well, I took at look at the truck again today for a while. From what I can tell it appears the previous owner put a throttle body on this truck from a 87 and up D21. I am guessing he was fighting the same issue I am dealing with and just gave up. From what pics I have seen in my Haynes manual the 86 throttle body did not have an idle up solenoid, only an FCID. The idle up solenoid was added in 87. My 86 has a 6 pin connector, 2 wires for the FCID and 2 wires for each injector. 87 and up had an 8 wire connector with the 2 additional wires being for the idle up solenoid. This explains why the idle up solenoid wires are just hanging there. Doesn't solve any of my issues though.

 

I drove the truck around for a while this afternoon but it's pretty miserable to drive at this point because of the lack of power. I did another compression check while the engine was cold and readings ranged from 132-139, only thing I did different this time was hold the throttle wide open. While these readings aren't very good I am guessing this isn't my problem.

 

The engine idles fine although a bit high and I can't adjust it any lower, sitting around 1050RPM. The engine rattle is still there at a certain throttle range/load, and when reving the engine up to 3000RPM and letting off the gas while sitting it spits and sputters out of the exhaust some.

 

I am tempted to get a fuel pressure regulator and make an adapter plate for my Weber carb and throw it on there temporarily to see if that fixes the issue. I read about someone else doing this with no issues. All he did was swap in the carb, add the fuel pressure regulator and drive it. He left the crank sensor in place. Link below.

 

z24i EFI, TBI, to weber carburetor conversion - Nissan Forum | Nissan Forums (nicoclub.com)

 

Here is a video of the truck running so the rattle can be heard. The sound is muted when you first open the video, you have to click the little speaker in the top right corner and adjust the volume.

 

https://imgur.com/a/71DWlem

Edited by powderfinger
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Look and see if you have an intake fuel pump or an on the frame rail pump.  It should be an on the frame rail as according to Nissan the first intank fuel pump was the 1987 D21 Hardbody.

 

Either buy a good used 720 carburreted fuel pump or a Facet Gold Flo FEP60SV Electric Fuel Pump Kit Universal Petrol & Diesel Electric Fuel Cylinder Pump

 

Facet-Gold-Flo-FEP60-SV-Electric-Fuel-Pu

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Good point Charlie, I have two working fuel pumps on my spare carbureted 720's I can just put one of those on there if I do give the Weber a try. I'll have to see how difficult making the spacer plate will be or if it is even needed, pretty sure the intake manifold where the carb mounts is different between the two. I have some fairly thick aluminum laying around I can use for an adapter plate if needed. 

 

Starting to lean towards giving this a try since I have all the parts needed unless the adapter plate is more difficult than I am imagining, all it will cost is time. At least it will tell me if this is a fuel delivery issue, whether it be an issue with the TB or computer related.

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That is definitely an option especially since I have a carbureted intake manifold sitting in the floor of my shop. The z24i has a water temp sending unit on the intake that the carbureted intake does not have. I am guessing the computer uses that signal to control fuel delivery, if so then it won't be functioning with the weber anyway so it doesn't matter.

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Well. I got an adapter plate made and got the Weber carb on the z24i intake but after getting that put on and swapping out the fuel pump for a low pressure pump off another truck now the fuel pump isn't coming on for some reason. I didn't have time to troubleshoot the issue other than to verify there is no voltage at the pump when the key is on. I may hot wire the pump just to make sure it's working, I know it was a few weeks ago. If I can get it working by hotwiring it I can at least see if the truck runs decent with the Weber on there. I forgot to take pics of the adapter plate after it was finished but i did get one of the standard adapter sitting on my manifold and another of the standard adapter sitting on top of the adapter plate I was working on before I finished it.

 

If the truck ends up running good with this setup I will probably go back and make a new adapter with the studs made into it for the weber instead of having an adapter that attaches to another adapter. Seems like I am just asking for an intake leak with two adapter plates on there but this will work temporarily.

 

 

IMG_1921.jpg

IMG_1923.jpg

 

I had to use longer studs on the right side because of the thickness of the two adapter plates. I removed the factory studs on the left side of the intake and used bolts to hold the first plate down to the intake. Had to trim them down to make them fit without hitting the other adapter. I made gaskets to go between each plate. Once again, certainly not ideal but hopefully it will be good enough to test it out. I wish I had thought of just making one adapter that mounts to the intake and the carb can mount directly to before making this intermediate plate, would have been much easier.

Edited by powderfinger
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I looked under there over the weekend because that's what I was planning to do and I believe this truck has a different relay than the carbureted models. I will look into this further but the original fuel pump and relay worked fine. Only issue was when I swapped in the low pressure pump which I also know was working a few weeks ago.

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The pump worked after wiring it straight to the battery. When I cranked the truck up the engine was making a loud whistling sound and I couldn't keep it running. Turns out I have a major air leak on the drivers side of the adapter I made where it mounts to the intake. Probably caused by a combination of the aluminum I used not being perfectly flat and the fact that because of how the adapters are made I had to tighten the passenger side of the bottom adapter plate down first before putting the second adapter on and then the carb. The nuts on the drivers side of the carb hold the carb and both adapters down. By tightening the passenger side of the bottom plate first I most likely caused a gap on the other side. I need to redesign it to allow me to tighten all four together so I am not putting torque on only one side at a time.

 

It also didn't help that the only gasket material Autozone had was fairly thin.

Edited by powderfinger
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3 hours ago, Charlie69 said:

I believe the is an adapter forthe Z24I.  I thought you were going to use a carb manifold.

 

I was thinking about using the carb manifold but decided at the last minute not to but now with these issues with the adapter I may just go ahead and switch over to it. 

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Well.....I decided yesterday to swap the intake manifold to a carbureted one to simplify the adapter situation with the Weber. Weren't we just talking about how most issues with vehicles were due to previous owners and their hack-job repairs. Well someone took the intake manifold off at some point, probably to fix a blown head gasket and put a mixture of different bolts back in it instead of all the factory ones. Unfortunately, three of these were very poor quality bolts that had rusted and started to seize inside of the head. I managed to get them all out but one. This one snapped the head off.

 

There was still about a half inch of bolt sticking out of the head so I tried to use vice grips to get it out but it's in there really good and just keeps tearing up the bolt and rounding it more. I then tried forcing a nut onto it and tack welding the nut to the bolt. I was very nervous about trying this because it is a bottom bolt right near the head gasket but I didn't have any other ideas. Got that tacked on and when I tried to get it off all it did was snap the bolt off nearly flush with the head.

 

I tried using an easy-out but I knew that was a waste of time before I even tried it. The steel the bolt is made of is garbage and it just rounded the hole in the bolt out.

 

There is just enough bolt sticking out that I can try welding another nut onto it but it makes me nervous being a bottom bolt and so close to the gasket. Not sure what else to do at this point. Drilling it out would be difficult without damaging the head. Especially because of the angle. I would need to get the head off and mount it on my drill press to be assured I am drilling straight.

 

image.thumb.png.1acbf8c9e7701de46afba2af71c0d89d.png

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image.thumb.png.1acbf8c9e7701de46afba2af71c0d89d.png

 

This will be easy. Adjust a pair of vice grips to hold onto those threads and remove them. Heat around the broken bolt, you can even heat down it's length inside the head, with a propane torch then spray the end with WD-40. do this 2 or 3 times to temperature shock the fastener's grip. Then heat as hot as you can, grip the threads quickly and twist out by hand. This has never failed me.

 

I may have had more to grip on with but if you do weld a nut on the end still try the heat and WD-40.  It may also help to get it to wiggle back and forth rather than force it towards loosening non stop.

 

EXPfNAS.jpg 

 

EYukARt.jpg

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Even if you weld that nut cherry red, you aren't going to cause any head gasket issues.  The head is a huge aluminum heat sink and will spread that heat very quickly.  I'm not familiar with even one instance where someone welded a nut to a bolt and the heat caused warpage to a cylinder head.  Do as mike suggested and hit it with a penetrating lube after you weld it.  You will remove a great deal of heat in addition to shocking the bolt.

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