datson4life Posted July 27, 2017 Report Share Posted July 27, 2017 Im in TJ visiting my brother and trying to help him get his truck running cause its a nightmare having to cross tijuana from on end to the other to get to work daily on a bus (calafia) Issue: truck turns on, drives maybe 5 minutes perfect and turns then turns off and very hard to get back to start. He has replaced: both coils, rotor, dist cap, fuel pump, fp relay Ive read there is a fuel pump control, would this model have that? Or what else could be checked Quote Link to comment
datzenmike Posted July 28, 2017 Report Share Posted July 28, 2017 Next time it quits check for... GAS........ look in window on front of carb. Gas should be in sight, usually level with the dot. Got gas??? SPARK... pull a plug wire off and put an old plug in the end, lay on a grounded surface and turn engine over with the starter. Got spark??? Stop throwing parts on it. Not only is it like trying to win the lottery, it's expensive and you are likely replacing good quality Nissan parts with shit from Taiwan that may even add another problem. Quote Link to comment
Lockleaf Posted July 28, 2017 Report Share Posted July 28, 2017 Fuel pump control module is only in electric fuel pump vehicles. This should be a mechanical pump on the motor. When it dies and won't start, check for what is missing. Fuel or spark. Quote Link to comment
datson4life Posted July 28, 2017 Author Report Share Posted July 28, 2017 He says its electric fuel pump. I will go look at it tomorrow Quote Link to comment
Lockleaf Posted July 28, 2017 Report Share Posted July 28, 2017 Then someone may have replaced the mechanical pump with an electric shock would add its own potential set its issues. Check to see if it still has a mechanical pump that has been bypassed. Quote Link to comment
datson4life Posted July 28, 2017 Author Report Share Posted July 28, 2017 Will do thanks Quote Link to comment
datzenmike Posted July 28, 2017 Report Share Posted July 28, 2017 Never seen any 720 without an electric fuel pump. All I have seen have a block off plate to cover the hole. The Z24s didn't even have a hole for the pump. Quote Link to comment
Lockleaf Posted July 28, 2017 Report Share Posted July 28, 2017 I have a z22 I personally pulled from an 82 720 sitting in my 510. Its mechanical fuel pump. Not even a provision for electrical in the wiring harness that year so far as i have seen in the wiring diagrams. I have always been under the impression everything pre Z24 was mechanical and the z24 introduced the electric pump in the trucks. Quote Link to comment
datzenmike Posted July 28, 2017 Report Share Posted July 28, 2017 It may be a Canadian thing. I remember seeing a Z22 at Canby and was very confused by the mechanical pump... which looked larger than the L20B pumps. 1 Quote Link to comment
datson4life Posted July 29, 2017 Author Report Share Posted July 29, 2017 So went over. The distributor was bad. Replaced it. Starts and has spark now cause before had spark on and off. In the process starter went bad. Rebuild starter. Starts right up, idles fine. But it turns off when its underload. Starts to bog down and just stops. I believe its a gas issue but i had to take off, they stayed to mess with carb Oh and yes the new taiwanese relay he installed was garbage. He three the old japanese one back in for fp relay. And yes its stock with electric fp Quote Link to comment
datson4life Posted July 29, 2017 Author Report Share Posted July 29, 2017 Ok. He says it all come down to the carb. Can anyone point the way to a decent carb for that engine? Would a 32/36 weber work? Quote Link to comment
Lockleaf Posted July 29, 2017 Report Share Posted July 29, 2017 Yes 32/36 carb is the most common swap inn these. I have one on mine. Works great 1 Quote Link to comment
datson4life Posted July 29, 2017 Author Report Share Posted July 29, 2017 Ok cool. And just start plugging up the hundreds of unnecessary vacuum lines? Rumor is to avoid the chinese webers, how can i identity difference between a good one and chinese one? Quote Link to comment
datson4life Posted July 29, 2017 Author Report Share Posted July 29, 2017 Forgot to mention this truck has 600k + miles Quote Link to comment
Lockleaf Posted July 29, 2017 Report Share Posted July 29, 2017 The only vacuum line you MUST retain is the vacuum advance to the distributor. Quote Link to comment
Crashtd420 Posted July 29, 2017 Report Share Posted July 29, 2017 Ok cool. And just start plugging up the hundreds of unnecessary vacuum lines? Rumor is to avoid the chinese webers, how can i identity difference between a good one and chinese one? Just order from pierce manifold and you'll get what you need.... they sell complete kits.... if you find it cheaper it's probably a knockoff..... Quote Link to comment
datzenmike Posted July 29, 2017 Report Share Posted July 29, 2017 Loss of power under load can be a $5 fuel filter. Can't supply fuel fast enough and carb runs dry under load. Quote Link to comment
datson4life Posted July 29, 2017 Author Report Share Posted July 29, 2017 Fuel filter was replaced Quote Link to comment
datzenmike Posted July 29, 2017 Report Share Posted July 29, 2017 If the primary barrel is not working properly it will still idle ok. Again, next time as it quits under heavy load, shut it off immediately with the ignition and pull over before the electric fuel pump can refill the carb. Check that the carb has gas in it. If this is a gas delivery problem (like a bad pump or clog in the line) a new carb isn't going to help is it? If carb is out of gas, maybe the inlet filter screen at the carb is blocked, maybe float is set too low... again the engine uses it faster than it is allowed into the carb and runs out. Easy fix or adjustment and cheaper than a $300 new carb. Quote Link to comment
datson4life Posted July 29, 2017 Author Report Share Posted July 29, 2017 Will do. I will head over to that side of town today and inspect fuel pressure Quote Link to comment
datzenmike Posted July 29, 2017 Report Share Posted July 29, 2017 You want to preserve exactly what's happening with the carb exactly when it happens in order to prove or disprove a thing. When it quits under heavy load, get the key OFF ASAP. Get the clutch in and safely pull over. Now you can inspect the carb as it was when it quit with little changed. If fuel level not evident in the glass on the front of the carb it probably running out. Kinked fuel line or hose or sediment restricting flow to or from the pump, float set too low, screen at banjo fitting on carb inlet part blocked If there is fuel in carb, possibly the primary jet is plugged, blocked or part blocked. Engine gets air but not enough gas mixed with it. Quote Link to comment
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