Fuel pump issue, or not?

[zer0swanvert]

Ok, I have a 93 240sx convirtable with a 98 KA24DE, 5-speed conversion, and am having issues passing emissions. Here is the details:

My friend used my motor to pass emissions and it was peppy and full of response. But, when I swapped the motor into my car, it was but that. Now I have mostly original parts. My car seems to have a great deal of loss of power. If u push the accelerator all the way, nothing happens. Although, when I 1/2 throttle it, it seems to be responsive, but very sluggish. It seems I am at roughly 90 hp, maybe? just a guess, but to put a picture on the power loss I experience.

The new parts that I bought made a slight difference. An exaust with a new cat. Fixed temporarily an exuast leak that is part of an egr system after the 02 sensor on the exaust itself. New O2 sensor and a new temp sensor. Still, my issues continue. Plus, the more I drive, the worse it gets, cutting off power compleately sometimes.

Now at emissions, I passed everything except for CO. And everything stayed stable, except CO increased each trip there. Passing level of CO is 12.00, I was at 12.48 for the longest time, strange I know, then it had rose to 13.20. Wtf was my response.

Now the only difference I could destinguish from the motor being in my freinds car, to my car, was our fuel pumps. He has a walboro, I have stock original pump. Could this be the main issue? Friday, I am purchasing a walboro fuel pump, which is a need anyways. So could a new walboro fuel pump fix this issue? Any Response would be appreciated, thank you.

[allenms240]

I wouldn't think so. My 2 cents. the fuel pump only supplies the fuel and since the motor is running, its clearly getting the fuel. I guess it could not be pumping ENOUGH fuel.

I had my motor in my 240 and it ran like crap, just like what you are saying. Major power loss and was extremely slow.Then I swapped it do a new shell due to a wreck.Now it runs strong, much much better than before. Everything was swapped, even the fuel tank and fuel pump. I don;t know why it ran better, it just did.

[poshatch]

i feel for you man, ive struggled with smog for kades before and its horrible, its going to be hard over the internet to diagnose cause its easier to see things

it is most likely something that happened durring the swap so just recheck everything and re trace your steps to make sure everything is connected and done correctly from spark wires and firing order right down to every vaccum line and plug

its unlikely that there is a problem with the engine if you didnt go into it and do anyhting

and btw. i had a walboro in my coupe and i have a stock in my current hatch and it didnt make the slightest difference to me, its useless to force more fuel in if you also arnt getting more air, just saying

id say give it a good seafoam too and see how that goes too...

could always run two cats

[numbnuts240]

for the hell of it (they're cheap) throw a new fuel filter in there. my first hatch was experiencing power loss like you're describing and it turned out to just be a clogged fuel filter.

[DrifterXRPS13]

when i failed my emissions on my old s13 i went out and did a full tune up...new plugs, wires, cap, rotor, changed the oil, new fuel filter, new valve cover gasket, flushed the radiator, the charcoal canister...pretty much everything was less than a $100 and did it in an afternoon...next time i went to get it tested, it passed with flying colors.

also might wanna check how your exhaust system is holding up...might be an o2 issue or your cat is clogged...good luck.

[Chris28]

Also check your fuel pressure regulator. If your friend was using the KA and had a walbro there's a chance the FPR failed right before or as you swapped the engine. I've heard that the higher pressure from the Walbro unit causes the diaphragm in the stock FPR to fail, resulting in inconsistent fuel pressure. Usually happens when people go KA-T, but the cause is the upgraded fuel pump.

Try a new fuel filter, new FPR, and new fuel pump one at a time in that order. The problem could be something else, but those things are easy and fairly cheap to replace.

Good luck.

[zer0swanvert]

That actually makes sense. Now if I purchase a new fuel pump, should I go with a stock one, or go with a walboro? I am thinking I will expirience the same issue if I install a walboro, but perhaps over time. I just need a reliable car right now. Just untill I figure out what I am going to build for this vert. What would be your suggestion?

[zer0swanvert]

for the hell of it (they're cheap) throw a new fuel filter in there. my first hatch was experiencing power loss like you're describing and it turned out to just be a clogged fuel filter.

I actually have a new filter, though the tank was not the cleanest, so I could clean it. It has only been on the pump for a month, so I gather through that time it may have become clogged. What would you suggest to clean the filter, if it was neccessary?

[zer0swanvert]

when i failed my emissions on my old s13 i went out and did a full tune up...new plugs, wires, cap, rotor, changed the oil, new fuel filter, new valve cover gasket, flushed the radiator, the charcoal canister...pretty much everything was less than a $100 and did it in an afternoon...next time i went to get it tested, it passed with flying colors.

also might wanna check how your exhaust system is holding up...might be an o2 issue or your cat is clogged...good luck.

The motor and all that you have mentions above is roughly 50k miles, would you suggest a tuneup at that stage? Of course, it could not hurt . O2 sensor is brand new. But the cat is welded to the exaust. So I would have to ask someone to cut off the old cat, weld flanges so I can BOLT in a new cat, (which found out my friend has, he had just found it actually, lol), and use it for emissions. Then latter on down the road, use a test pipe, and have the cat for emissions only. Just need someone who can weld . . .hmm . . .

[rioredstang]

Have you check ecu for codes? This is the first place to start. Then you should check all the basic tune up specs. Idle speed and ignition timing will effect HC & CO levels greatly. 1. Check codes--2. Set base tune up specs-- adjust idle to the upper limits of specs. Higher idle will clean up HC & CO levels.3. Check cat for restrictions. Its still working, but may be plugged up.Check these and let us know and we will help.

[Inabj2]

Dude, just get a new fuel pump.

A walbro has higher pressure then stock, but 10 miles total trip is not going to kill a FPR. It has a slightly higher pressure then stock too, its not like were doubling the pressure. I have 2 walbros on my setup and my FPR is fine.

You forgot to mention that car runs fine when its cold, and it gets progressively worse as you drive. So that would rule out a clogged cat, since then it would run s***ty at all times.

[allenms240]

Hmmm, the fuel filter we're talking about is the one in the engine bay, not on the fuel pump. Its on the passenger side of the bay and comes off the fuel rail. Replace that and see if it fixes. Then you can try to seafoam. I had seafoamed mine motor right before i swapped my car from shells and now its running stellar.

[J14cm7]

Im surprised no one has suggested MAF or a vacuum problem. Does the car idle fine? If the car idles fine i would steer away from a fuel issue and focus more on air. Why would you need a bigger fuel pump for a stock KA? Keep the stock one and try to diagnose the problem before you spend a bunch of money on something. Probably just something simple

[allenms240]

Dirty or bad maf would cause the car to idle funky? It doesnt sound like that is his problem because of that. a Vacuum leak would do the same think. I dont think its because you have a OE fuel pump though becuase they come OE for a reason, because they work. Try seafoam as said before. Make sure all connections are made from the motor swap. Like I said, when i moved the motor from one shell to another, It ran jsut as you described earlier in the first shell. I swapped it, then it ran much better. The only think i can think of is i seafoamed the crankcase, the vacuum lines, and the gas lines. Then it ran flawless. only thinks i can think of is that, or the connections were made correctly when swapped.

[PeterKesel]

Thanks for this thread, the fuel filter we're talking about is the one in the engine bay, not on the fuel pump.

[J14cm7]

Dirty or bad maf would cause the car to idle funky? It doesnt sound like that is his problem because of that. a Vacuum leak would do the same think. I dont think its because you have a OE fuel pump though becuase they come OE for a reason, because they work. Try seafoam as said before. Make sure all connections are made from the motor swap. Like I said, when i moved the motor from one shell to another, It ran jsut as you described earlier in the first shell. I swapped it, then it ran much better. The only think i can think of is i seafoamed the crankcase, the vacuum lines, and the gas lines. Then it ran flawless. only thinks i can think of is that, or the connections were made correctly when swapped.

With a bad or dirty MAF his car would start to struggle about 2500-3000 rpms in my experience. Search around there are tons of threads on thisl.

[allenms240]

Thanks for this thread, the fuel filter we're talking about is the one in the engine bay, not on the fuel pump.

Lol?

Well it doesnt sound like a dirty MAF. Dirty MAF causes the car to idle funky and bog out. From what your describing, the motor runs fine and everything, its just slow.

[J14cm7]

Lol?

Well it doesnt sound like a dirty MAF. Dirty MAF causes the car to idle funky and bog out. From what your describing, the motor runs fine and everything, its just slow.[/QUOTE]

Idle funky? hmmm...tell you what do me a favor and go out and start your car up and unplug your maf you will notice that the car drops rpms but still idles fine and now it seems like the car isnt runnin as strong. I wish people would post the final solution to these problems so we wouldnt have these arguements.

[allenms240]

Go out. Unplug the maf. Step on the gas. It bogs the car out. And it also idles funny. You also cant get high Rpm witha bad maf. Maf doesn't sound like his problem. No reason to get defensve

[J14cm7]

I believe i stated it would bog out. Not getting defensive. You stated that the car would idle "funky". Now we are agreeing that it idles fine, just at a lower rpm than normal. Glad we are in agreement.

[brokeded]

OMG if the tank has not been cleaned since the car was bought......keep in mind, it is an older car WITH a metal tank bonus..............get it boiled and coated..............use compressed air for the lines........get a new filter.........done. the same thing happened to me when i bought my 92. all of the above got it running like a champ