Struggling Hardbody

[dutchogj]

I have a 1989 Nissan Hardbody with a Z24 and California emissions.  The engine has been decked and bored, with a new distributor, head and cam.  It also has a Pace header, new fuel pump, new fuel injector, fuel filter, and the computer has been replaced with one from California from a vehicle with the same type emissions.     

 

This vehicle is starving for fuel.  I cannot figure out why it would be doing this.  Can anyone help?

[jesusno2]

Air leak possibly?  Numerous reasons, really. Not familair with early TBI systems is it running at all?

[dutchogj]

Yes, I drive the vehicle. I love this truck and I will keep it as long as I can.  I just wish I could get it running properly.  If I attempt to take off hard, the engine stops accelerating.  It seems to just stop receiving gas.  I have not attempted to do anything to the emissions other than clean out a filter container located on the left inner fenderwell area.  The container was rusted and had been seemingly clogged to a point that no air could ever pass through.  The problem with this is that prior to rebuilding the engine this canister was still clogged.          

 

During idle the engine will occasionally run fine, however, after having driven it for a while and it sits for 15-20 minutes it takes a while continually revving the engine until it "clears up," left alone it would die.    

During driving at any time if I attempt to downshift and accelerate the engine sputters and I have to pump the throttle to get to a higher rpm before I release the clutch.  

I also have to repeat this procedure under hard take off which makes city driving a bit hairy.     

[]2eDeYe]

Collapsed line or bad pressure regulator are my second and third guess after reading the symptoms. Have you checked to see if you have a plugged catalytic converter? 

[nerdistmonk]

Have you pulled the codes on your engine management computer yet? it will give you a clue as to what may be wrong, do that before spending money.

[HRH]

No usable codes off that computer.  Doesn't really interface with anything.  Too old.  KA got the blinking lights version that you can count to diagnose, pretty sure Z24i missed that.  Anyway, check your tps switch, make sure all three points are working correctly.  Next, check your distributor, and make sure it's timed correctly.  Report back.

[flatcat19]

Did it work before all these parts were replaced?

Why were all these parts replaced?

 

Why does it seem like there is always a small, but vital, piece of information left out?

[datzenmike]

 It also has a Pace header, new fuel pump, new fuel injector, fuel filter, and the computer has been replaced with one from California from a vehicle with the same type emissions.     

 

This vehicle is starving for fuel.  I cannot figure out why it would be doing this.  Can anyone help?

.

How do you know it starving for fuel? What makes you think this?

 

I see lots of replaced parts that could be bad and the cause of the poor running. If you have the old ECU put it back and see if that fixes it.

 

 

Assume for a minute that all the above is good. Have you checked your valve lash.. 0.013" on both sides. How are your rotor, cap and wires? Timing around 3 degrees?

[nerdistmonk]

No usable codes off that computer.  Doesn't really interface with anything.  Too old.  KA got the blinking lights version that you can count to diagnose, pretty sure Z24i missed that.  Anyway, check your tps switch, make sure all three points are working correctly.  Next, check your distributor, and make sure it's timed correctly.  Report back.

 

the z24i has a fully functioning obd1 ecu that will give useful codes without any sort of reader, i know mine did right before i yanked its sensors (if there was a code for missing engine thats what mine would say :P ). Complete with safe mode whenever a sensor goes bad or an injector malfunctions. It has a pair of blinking lights that you count just like the ka (also obd1) and 5 modes of operation including mixture readouts.

 

Edit: when its in safe mode, the engine will just cut out after a certain position on the throttle (2800 rpms or so), you have to ease it up to speed or it starts bucking like a bronco and can backfire on occasion.

[HRH]

Huh, I stand corrected!  I didn't think the Z24 models came with that.  Good to know.  Makes me wonder how easy it is to put a KA system in a Z24i hardbody.  I'm thinking most of the wiring needed might be there.  The fuel pump should be as much pressure with the dribbler injection, but I'll have to check that.

[nerdistmonk]

Huh, I stand corrected!  I didn't think the Z24 models came with that.  Good to know.  Makes me wonder how easy it is to put a KA system in a Z24i hardbody.  I'm thinking most of the wiring needed might be there.  The fuel pump should be as much pressure with the dribbler injection, but I'll have to check that.

 

That reminds me according to schematics the ecu on these trucks control the fuel pump relay. As for putting a ka ecu on it, i think the problem might be in the sensors, im not sure if the z24 sensors can talk to the ka24's ecu, also the pressure on the z24i's pump is 35psi i think (mine was dead so it was 0 lol). Your other big issue is the ka ecu is programmed for multiport injection is it not? it probably wont talk to those old dribblers. Then again you can certainly try, it would be another first for the nissan hardbody. B)

 

The ecu seems to "control" things by switching the ground wires to said components on and off which is how it signals the coils to time the engine using the signals from all the sensors.

 

Mine had a bad maf and a dead injector, it ran horribly, its likely his problem isnt too far from what my problem was, the bad part is the maf may not report on the ecu since it can be making a partial connection and if it isnt a completely broken connection the ecu wont say a thing, as for a dead injector he can visibly identify that by taking the breather off and looking into the TBI with a flashlight (look for 2 sets of sprayers going).

[yellowdatsun]

If it idles fine, and drives at cruise speed fine, yet has problems under acceleration, it likely IS starving for fuel. Could be a clogged filter, clogged line, clogged strainer at the pump, etc.

 

What "filter canister" are you talking about?

[dutchogj]

Hello everyone,

Thank you so much for all the information.  To date I haven’t changed anything yet but I am happy to see I found a source where individuals are passionate about their Nissans. 

I will attempt to answer your questions and/or reply to your comments in order.

The catalytic convertor is new.  I worried about it some time ago and double checked it.  It seems fine.

The tps has been changed and if I am not mistaken seems to be working fine.  I had received instructions on how to adjust its mounting position from the dealer.  I can’t help but wonder if somehow I just didn’t get it mounted in the correct place to ensure accurate functioning.  The distributor is also new and the timing is set at 10 degrees.  I hope this is sufficient for proper engine performance. 

The timing is the reason for the replacement of “all these parts.”  Before the engine had been rebuilt I was experiencing a fluctuation in engine idle.  Unfortunately, due to a horrendous mistake on my part the timing was set originally to a point where I thought would be safe.  In other words I wanted to maximize performance so I advanced the timing higher and experimented, waiting to hear pinging.  I never did.  I set it at the low point (during fluctuation) which proceeded to cause the timing to be too advanced during acceleration.  A hole in a piston was the result.  The engine had 287,000 miles on at this point so the result didn’t bother me much.   

I have not checked the valve lash.  I will take this into consideration.  Cap, rotor, and wires are new.  Again, the timing is now at 10 degrees.  I still experience some slight fluctuation at idle so I’m a little gun shy. 

I am not familiar with the term “safe mode.”  I very happy to have read this since your description seems to fit some of my symptoms.  Could you possibly expand on what “safe mode” is for this vehicle?  I would also appreciate any information as to how to correct this. 

The line pressure at the throttle body is 38 lbs.    

The “filter canister” I referred to is a part of the “California emissions” requirement.  It sits on the left (driver’s side) fenderwell.  There are several hoses going to and from this.  When rebuilding the engine I opened the canister and found a rusted and clogged compartment.  There used to be a filter in it, however, it had deteriorated so I removed the debris and cleaned everything as best I could.  I reconnected the hoses and hoped for the best.     

Thanks for all the responses.  I will monitor this forum and I look forward to further instructions.  Please keep it up. 

[datzenmike]

All vehicles with have the canister. It contains activated charcoal and can absorb fuel vapors from the gas tank or anywhere else and store them rather than letting them escape into the air. On start up manifold vacuum sucks them into the motor to be burned. The system has ZERO effect on the running of the motor. If you gutted the container there is nothing to hold the vapors and you may notice gas smells. That's about it.

 

'safe mode' may also be known as 'limp home' mode or ' default mode'. This is a pre set, over rich mixture that is supplied if there is ever a failure in the metering system. Because of the O2 feedback very lean mixtures are possible that could cause a piston failure so a rich mixture is selected. This is meant to get you to somewhere for proper servicing and not to be driven unfixed for any great length of time.

[HRH]

Take some good pictures of your engine bay and post them.  There might be something obvious.