need some advice

[neff]

hey guys I've search the forum and seems to be no definitive findings.
i have a early 4.0 V6 it seems to be surging slightly under load at speed, no problems starting.
I'm thinking it may be the fuel pump as i have just kicked over 200000km, I've had stuffed/failing pumps in the past.
service not long ago replaced the filters, always run on 98 from decent stations.
the genuine price for the fuel pump is $791.91
thinking of just using a standard Walbro 255 for a replacement
I've used RockAuto.com for parts before from the states but searching under Tacoma there is a OEM Denso parts listed for $97.00 or so but always run the risk that it MAY not be the exact part i need.
Question is has anyone had experience replacing the factory unit with a Walbro or like??
i have modded walbro pumps to fit other units before theres not much fuss really but I've read a few things about duel stage pump in the V6.
any help guys would be great as i don't really want to drop $800 on a pump.
cheers

[anthony kemp]

walbro make a hi pressure external inline fuel pump that you could use for now as it will take pressure off the intank pump... this wont fix the problem but will sort it out till you do more homework and find out what will fit.$790 for a fuel pump if day light robbery what a joke

or you can try this universal kit for hilux:
http://www.ebay.com.au/itm/NEW-Walbro-2 ... 3cd9e43f20

pretty sure its the same model in my 355 stroker . great pump so far no dramas and alot quieter then bosch 044

[boxhead55]

I have never replace a pump yet as they speed up and slow right down when not required.
This makes them last a very long time.
Hover I have ganged many many sets of blocked fuel injectors and the symptoms you describe point to that.
A fuel trim test will prove or disprove that theory!

[neff]

thanks guys, I'm going to take it for a scan see if its showing a code,
I will post my findings

[rysermon]

my guess is injectors need cleaning or blocked fuel filter..

[boxhead55]

It won't show a code they will have to check your long term and short term fuel trims

[neff]

OK I'm going to do my injectors (RockAuto.com) I highly recommend the site...
shortly before my 210k service will keep posted.
had a similar problem with a B4 subaru turned out to be the crank angle sensor.
appreciate the input guys.

[1NCH2]

Any luck with the surging issue? Mine had started doing it around 3000 rpm when under 50%+ throttle. Just wanted to get an idea before i start throwing money at it.

[jimmi]

i've had the same prob too, feels like turbo lag, then fine above 3000 rpm, my ecu light came on, o2 sensor melted wiring.
Are you running after market exhaust?
have you got techstream?
where are u located?

[1NCH2]

I replaced the fuel filter, was full of black gunk. Feels better under light throttle but seems to miss at idle if i stab the throttle when idling along in 2nd or 3rd. I'm running the trd iridium plugs and checked them, they aren't sooting up at all. There is a loud exhaust leak sound from around the number 5 cylinder under load. I'm beginning to wonder if the intake manifold may have a dodgy gasket or leak somewhere causing it to lean out. Getting frustrated with this car.

[jimmi]

I replaced the fuel filter, was full of black gunk. Feels better under light throttle but seems to miss at idle if i stab the throttle when idling along in 2nd or 3rd. I'm running the trd iridium plugs and checked them, they aren't sooting up at all. There is a loud exhaust leak sound from around the number 5 cylinder under load. I'm beginning to wonder if the intake manifold may have a dodgy gasket or leak somewhere causing it to lean out. Getting frustrated with this car.

take it to work, ask one of the spanners to put a scan tool on it

[1NCH2]

Well its kind of awkward that you would say that. I am a spanner hahaha. But this is new ground for me having only worked on diesels. I chucked a scan tool on it today and nothing jumped out at me when i was graphing timing advance or o2 sensors/lambda however the short term fuel trim seemed to have a dip as the car had its flatspot/surging moment. I'm assuming now that its a fuel pump or injector issue as the sparkplugs are fine. But I'm damned if i can work out where the exhaust leak is as there's no soot build up anywhere.

[jimmi]

vaccum leak maybe, spray some wd40 on vac line near fuel regulator.
if it was an injector, the ecu would try compensate for it, you would see it on the scan tool.
fuel pump would get worse as rpm rises, but use a 0-100 gauge (care of the friendly B1 store) check it after fuel filter

[1NCH2]

Cheers jimmi. I have been doing heaps of research into long term and short term fuel trims and finally understand what i am looking at. Will have a geez when i knock off in the morning. Beginning to think that it could be a result of me having changed the battery a while ago and the ecu having lost its long term fuel trim figure for that given rpm and engine load. Which is why under 50% throttle it is fine because it has been in that condition regularly as opposed to over that as i dont hammer the poor girl everywhere. I'll give it some more time and wait until i can accurately check the parameters, until then I'll monitor how everything adjusts before i get too into it.

[jimmi]

nurries, there are a couple of YouTube clips on fuel trim, long term will normalize after about 90-120 sec on the v6

[1NCH2]

Yeah fuel trim is perfect through the rev range except around 2-3k rpm at over 50% throttle where it follows the normal cycle of lean-rich sin wave but suddenly has 2 huge lean events before flat lining at 0% for a period of time. If you watch the following video at 54 sec i start with full throttle rolling in 4th and it leans out heaps as it should before adding fuel and equalising but then had 2 huge lean events and flat lines. It doesn't do it in any other rpm range as i have checked, i hey the first lean event then it equalises and continues in closed loop. It's almost as if during the flat spots is going into open loop which it shouldn't being at operating temperature. https://youtu.be/NsytsohlODU

[1NCH2]

Well I've convinced the missus to let me get extractors after Christmas as it literally sounds like i have an exhaust leak of some description, or as she likes to say "all the killa-wasps have escaped and the crickets have moved in" hahaha
And i read somewhere that even pin holes in the exhaust before the oxy sensor can create lean events. Trial and error i guess, here's to hoping it doesnt get ridiculously expensive.

[jimmi]

i have a set of stocky ones, if you wanna try em first, only thing is postage from darwin

[1NCH2]

Nah, all good thanks. I have a spare set off a spare engine i got with the car when i bought it. Swapped them over and it seems much better. I think part of the problem is that the mob that swapped the engine before i bought it didnt use a gasket between the manifold/cat section to the middle section where the second oxy sensor is so i reckon there's a good chance its contributing to the issue. How ever i will still get extractors. Just incase haha

[1NCH2]

Didn't realise that the intake is a dual runner intake. I think theres a good chance the valve that actuates the runners could be gummed up after 270,000kms. Something else to clean. Yay.