presumably fuel delivery problem

[metrickillers]

hey guys, so i have had this problem since the day i bought my 77 280z, and nobody has been able to help me fix it.the problem: when it first started it would sputter and backfire at about 3000 rpm and get worse as i drove it. as time went on the problem got increasingly worse and became kinda undrivable. I found started investigating and found that the fuel pump would pulse and shut off then return "repeat". this would obviously  cause the engine to starve for fuel and sputter or stop firing all together. well i bought a brand new "presumably a real walbro 255 fuel pump" and replaced the stock fuel pump with the walbro. the z ran amazing for about a month and a half. then started sputtering, backfiring,dying, just like before. at a glance it seems the fuel pump went out again but i find it hard to believe that it would just burn up and die in a month, although i have ran under a half tank about the entire time its been installed, but i didn't think it mattered much on a external pump.  it has to be something electrical,fuel pump, afm, tps,realy, something along those lines. As of now the 280z is litraly un-derivable. it will start and run great for about 3 seconds then starts acting up, i can drive it for about 50 feet then it gets so bad to the point were the pump is barely functioning and cant touch the throttle  without it dying, it eventually just dies. im at a loss here guys, this is my baby and would love to drive her on the road once more. help or opinions would be greatly appreciated  

 

additional  -info: when i turn the key too acc the pump comes on and stays on. "i don't think this is normal" 

                 - the afm that is on the car right now  might be from a zx, the owner gave me a box of parts and there was a was looks to be a zx n/a afm, i know that some people do the zx afm conversion. i also know that the early 77 280z had a fuel pump cut off switch in the afm's and the later ones did not and it was run from the oil pressure sensor. from what i can see the OPS operates just find and when it is unplugged it does not in anyway effect the pump or running status of the z. 

                 - the only thing on the car that i know does not work properly is the temp sensor. but i know that thats the reason its making the car run lean,if that was the issue that doesn't enplane why it ran great with a brand new pump.  

[datzenmike]

Is there a filter before the pump.

[Beau_]

+1 for the fuel filter. Im sure youve checked that, but thats what it sounds like to me.

 

FWIW I had a car that we put an electric pump on and we you turn the key to the on position, you could hear it buzzing away, all the way in the cab.

[metrickillers]

@datzenmike, to be honest im not sure, but i don't think so. @beau_ it might sound stupid but , no i have not checked the filter. i was thinking about it being the filter but i think that is not the problem. you can here the pump pulse, like its loosing voltage or having a random hard time to pump " kinda sounds like its seizing" . could a  severely clogged filter cause pressure in the lines to were it could effect the pumps functionality?

 

[Interrobang]

I might have missed it, but have you changed out the fuel filter? Old ones, besides getting full of sediment and rust, sort of turn into a ball of pulp that can block the inlet/outlet. If you haven't, try that, and flushing the lines.

 

There are also ways to test the fuel pressure. You can probably rent one at AutoBone.

 

Here's an L-Jetronic troubleshooting guide: http://manuals.type4.org/ljet/

[datsunaholic]

Funny, those symptoms are exactly why I got rid of my '77 280Z. I replaced damn near every part of the EFI system, only to have the exact same symptoms come back like clockwork every 1500 miles. 2 AFMs, 3 ECUs, 2 fuel pumps, a set of injectors, 2 sets of fuel pump relays... all in under 5000 miles. All were bad, too. But the clincher was it eating ECUs. And the temperature sensor was bypassed too, which was the only way I could get it to run (but I had to connect it to get it to START). The real problem was likely due to the car having been stolen at one point and partially stripped, and the wiring was somewhat suspect. That would explain the short ECU life. I simply got sick of it, it ran great when it ran but that had gotten so rare I gave up and traded it for a likewise basket case 510, but at least the 510 had obvious, repairable problems that didn't come back once fixed.

[metrickillers]

@datsunaholic. that is terrible,i love this car more than life i would hate to give up this amazing machine , but the ecu as far i i know is just fine the efi system looks like it is working properly. @interrobang no u haven't changed the filter but i am going to do so today. i was also thinking that maybe something in my tank is blocking the fuel outlet " to pump" like a floater or some piece of some of the tank itself.  im going to attempt to wire the pump from the battery and control it with a switch " temporary" to see if it solves my problem  

[I'm BLUE]

Go to xenon.com and download the factory service manual for yours ! ( easy to read and even EASIER to use ... just use a multi-meter )

 

You do need to conduct a fuel system pressure test ... after cleaning out your pump , replacing the inline filter ,,, and especially replacing any old lines on the system that are even slightly questionable !

 

The sounds of the fuel pump seizing usually has to do with the fact that their is

(A) Not enough fuel being supplied to it

( B) Fuel Pressure regulator is bad

© Internal Fuel pressure relief valve is stuck/bad (not likey and I only refer to NISSAN type pumps on this one)

(D) Clogged Fuel return lines.

(E) Clogged Fuel Pump/Fuel Pump filter if applicable (via crap in your tank ... NISSAN pumps have a mesh screen just like a Holley 4bbl at the inlet)

(F) Air in the system or being bled it in via bad lines/leak in the tank... bad fuel pump dampener .... etc ...

 

Check for vacuum leaks especially ... Nissan recommends around 10,000 mile interval replacements and no one ever does !! ( very few )

Vacuum hoses are hard to determine if leaking by eye ( no really just like electrical ) For as cheap as they are REPLACE THEM.

I can't tell you how many datsun's I've replaced and bought a crapload of vacuum hose for ,,, only for it to be the issue.

 

*Check your O2 sensor/wiring to it... and be VERY careful in testing it ...

*Make sure you don't have a clogged catalytic converter or muffler ( pull the pipe down ahead or behind it and test drive for 3-5 blocks ... no more so neighbors are happy )

*I pull the fuel rail (carefully) with injectors attached ... and activate the injectors with some seafoam pressurized through a closed loop system with a seperate fuel pump/lube.

*Check you distributor shaft play .... if bad enough ... you'll have ALL kinds of issues that you'll never be able to fix !

*Check your timing chain stretch ... ( this alone will cause a few headache's including power issues )

*Typically ALL Bosch EV-1 connector types ( nearly all of them on your 280z are ... ) should be replaced at one point or another.

*Open up and test TPS as well as clean/check the connector to it via xenon.com fsm download.

*The THERMO-Timer switch is pretty important ... check it ... and the connector (Bosch EV-1) via fsm at xenon.com

 

Wiring is typically the main issue with zcars ... like any other datsun.

Go to Xenon.com ... download the FSM ... read it , live it , love it. It can tell you nearly everything you want to ever know about your 280z faster than US.

 

You need to read your spark plugs for consistency in burn ,,, if Inconsistent .. or lean there are a lot of things to check

 

Test your AFM's resistance ,,, make sure the flap opens WItHOUT any physical bind ( smoothly ).

The connector's on these are usually at least half-way crapped out I might add and ... even better news you can still buy them !

 

Make sure your throttle body isn't glued shut with crap ( or near lol )

 

If you live in a high rust/rot area (salting on the roads) ... it's likely your rubber fuel lines.possibly metal fuel lines :confused: are close behind as well.

Make sure to replace the fuel lines ,,, and don't buy the fuel hose line that is less than $3.50-$4.00 a foot. If you do it'll be a short time before you'll be underneath/on the car replacing the lines again..

Good luck on finding larger fuel line locally ... may have to order that crap off the interwebs. (been through it a couple of times)

 

Relay's are common to be intermittent and go out.

 

Ignition module connections/distributor connections ... very common ... clean/replace as needed

 

Important Note: Before you waste your money at throwing parts at your datsun ... I'd like to add ... I have open up engine harness's a few feet back ... and even though the wires look "insulated" and protected 2 wires were corroded straight throught the insulation nearly all the way to the ECM plug. This is why it's really important to follow the FSM guidelines and testing procedures via Xenon.com.  Did I mention Xenon.com ? I thought I mentioned Xenon.com. Well anyway's incase you forgot it's Xenon.com for your 280z.  ;) ( I hope that was annoying because that means it will stick :D :lol: )

 

Just remember that a "Brand New" Part doesn't mean it will necessarily work. Especially nowadays even though the quality relatively to the time period is "better" than it was in some regards.

 

Don't go throwing parts at your car ,,, get frustrated with time and cost ,,, and then not have anything to work with in the end :)

 

A Nissan OEM pump is more than you need ... I don't know why you have a Walbro 255.

 

Relay's are intermittent as well when they start to go bad ,,, or stop all together when bad "enough". (keep that in mind)

 

Viya Con Dios !

 

Dtp

 

 

P.S ( I've repaired multiple 280zx's ( but am definetly not a pro-mechanic ) ... practically the same thing .... this one is one of my old ones with 226k on the clock WITH a broken speedo cable/unit .. http://portland.craigslist.org/wsc/cto/3643889549.html ... they obviously want a lot more than I sold it to them for lol )

[metrickillers]

thanks @dtp,  have done many of these test. and they all seem to come out normal :.

-clogged muffler/cat . i have a hollow cat and the muffler is fine,

 -AFM i just took off yesterday and everything looks normal"clean no corrosion"   the flap isn't stuck it works just fine,  

- Ignition , brand new plugs, coil, and as far as i could tell distributor is fine. timing is off but not bad, "cant fix at the moment" dont think timing is the problem in this case. 

- EFI/Injection is fine working normal. i could apply seafoam but they open and let fuel fairly well when its not acting up. 

-the tps is probably the only thing i haven't really looked at much, the connector look ehhh ok "could be cleaned" but i dont thing that is the issue in this case. 

- blocked line/pump; could very well be the issue, i live in utah so lots of salt could have made the tank corrode in turn blocking fuel or getting caught in the pump. im going to go replace the filter right now and i will let you guys know if there was a difference

-relay, the pump does sound like its getting drops in voltage so im wondering if the relay is going out, but it only happans if the car has been running for a a little bit, if it was a relay i would think that no matter when it starts it would just happen instantaneously 

 

other info: today i checked the old stock pump and ran it off of a 12v for a while. the pump "even after having been left out in snow for a year" worked just dandy. it did not pulse/shut off like it did when it was connected to the car.  so i think that i could probably rule out pumps. 

 

One question; after i replaced the pump with the new one the car ran great for a while then the same symptoms started again  i dont understand what would cause a car to do this if its not the pump.  

[metrickillers]

oh and i have become somewhat   familiar  with the fsm over the last year 1/12 haha but thank you. 

[metrickillers]

"update" i changed the filter and the z seems like it wants to actually run good now. the pump, as far as i could tell isnt pulsing and or struggling  to get fuel. i will let you know how it is after i drive it around for a while. 

[slowmomiata]

if its driving good with a new fuel filter thats great, i wish my problem was

that simple, my fairlday will only run WITHOUT an air flow meter lol

[I'm BLUE]

if its driving good with a new fuel filter thats great, i wish my problem was

that simple, my fairlday will only run WITHOUT an air flow meter lol

 

Didn't you sell the fairlady ?

[slowmomiata]

no the buyer fell through, every weekend i was promised he would come pay and pick it up and that dragged on for a month and i have known the guy for years, well i got sick of it and told him to basically kick rocks, bought a fuel pump and got her running, i am glad i did i just have issues to work out, i wrote up a thread about it, it fought me every step of the way but its running, i am sorry about the fs post, i trusted the guy would actually buy it he is a family friend but now just a d bag, i take it as a blessing in disguise i am glad i didnt sell it now its a fun great car just its acting weird

[metrickillers]

"Update" the car is at the shop at my school so im working on dropping the tank. i are almost positive that there is debris in the tank. so when im done with that i will let you know how it runs and if i fixed the problem. and sorry to hear about your z @slowmomiata i hope you find out whats wrong with it. 

[metrickillers]

"late update" it was the fuel tank, i was full of old hardened fuel that would almost instantly  clog ,lines,pump, filters, thank you guys for the help!