Goat Posted October 6, 2012 Share Posted October 6, 2012 Oh hay, im getting quit confused with some weird starting problem. Right, its a S4 13b turbo. Factory everything. It doesn't have the o2 sensor plugged in, and the fuel pump has a sweet under dash on/off switch (this only switches on power to the factory relay etc, so when this is switched on, it runs fuel pump as standard, i.e only pumps when cranking etc. Off = fuel pump off). So, the problem is, it will never start with the fuel pump on. If i have the fuel pump on (so just like factory), it will cough and fire maby once a second, but will never catch. (30 secs cranking and it is just flooded as hell, but it still bangs once every rotation) It starts and runs like a boss if I: [*:yrkb03de]Turn fuel pump switch on.[*:yrkb03de]Crank till it coughs.[*:yrkb03de]Turn fuel pump off.[*:yrkb03de]Crank for 2 seconds then it bursts into life.[*:yrkb03de]Then i turn the fuel pump on and it runs like a dream. (If i don't, it dies after about 6 seconds and i have to restart this whole procedure) Wat is this? I am confused as hell? Too much fuel pressure?? This seems weird and i would like it to just start normally without this on/off mumbo jumbo Any ideas you rotor fiends? Thanks a mil Pic of an fc cos they are pine as: Quote Link to comment Share on other sites More sharing options...
NicT Posted October 6, 2012 Share Posted October 6, 2012 Interesting problem, the factory ECU should have a fuel pump relay output that should control the fuel pressure priming. What happens is when you turn the key in most EFI setups is the ecu will prime the fuel rail for 2 seconds, let it crank without the fuel pump running then start the fuel pump after the engine catches. However if the engine cranks for more then 3 seconds or so the ecu will engage the fuel pump relay and turn the fuel pump on depending on the ECU (age, car, brand, im only going off toyotas as this is 90% of what i have worked on) I wouldnt have thought that this would be a problem however as when i wired up some ECUS when i first started out, it is wired so the relay engages when the engine is cranking in the starter position then engage properly when the car is up and running in the on position (this is not ideal as when you have an accident the fuel pump will run even when the engine is not turning over so i have stopped doing this and run the fuel pump relay off the ecu now) cause i secretely love rx7s Quote Link to comment Share on other sites More sharing options...
shizzl Posted October 6, 2012 Share Posted October 6, 2012 i had a similar issue with my first fc3s..i didnt have a switch though, but what i had to do if it would fire after a few cranks,was pop the bonnet, pull the injector fuse,crank it over,replace the fuse and start it. it had leaky injectors.... so it was basically overfueling on crank up,flooding... Quote Link to comment Share on other sites More sharing options...
kpr Posted October 6, 2012 Share Posted October 6, 2012 it had leaky injectors.... sounds something like this to me. get them tested. flicking the pump on after you start cranking should start it. Quote Link to comment Share on other sites More sharing options...
Goat Posted October 6, 2012 Author Share Posted October 6, 2012 Oh yup, thanks for the info guys. Do they have like a cold start injector etc that could be stuck open? Cos i have had it starting a few times without this fuel pump saga. After my initial attempts at starting it there was fuel literally flowing out of the back of the turbo... So was super SUPER SUPER rich when cranking. I'll check the fuel pump runs and stops when the ignition is turned on. Im sure it does, as when i first tried to get this going (over a year ago) i spent most of a weekend trying to get fuel pump running. It had horrifically shit installation of an immobilizer that cut the fuel pump. So pulled all that crap out and put a switch on the butchered fuel pump wires (for a manual immobilizer). I hope the fuel pump doesn't run all the time. Will confirm this. Will get injectors tested. But yea, have got the starting recipe sorted. And it will start every time if i turn fuel pump off while crankng. But would rather not have to do this. haha. Thanks again! Much appreciated Quote Link to comment Share on other sites More sharing options...
kpr Posted October 6, 2012 Share Posted October 6, 2012 don't think they have a cold start injector. pretty sure mates s5 didn't anyway. possibly an ecu issue if its firing that much fuel out. trying another is worth a got winding over at decent speed? ecu can get some wack rpm signals if not. Quote Link to comment Share on other sites More sharing options...
shizzl Posted October 6, 2012 Share Posted October 6, 2012 fuel pump wiring in these is super dodgey anyway, and the factory pumps do shit out. Quote Link to comment Share on other sites More sharing options...
Dell'orto Posted October 6, 2012 Share Posted October 6, 2012 ECU does all sorts of funny shit too, my FC did this too. I used to just leave it sitting for 15 minutes, then come back and it'd fire almost instantly. Quote Link to comment Share on other sites More sharing options...
shizzl Posted October 6, 2012 Share Posted October 6, 2012 best thing i did with my s4 drift pig was put a link in it....started mint every time. Quote Link to comment Share on other sites More sharing options...
Goat Posted October 7, 2012 Author Share Posted October 7, 2012 I have another ECU to try.. Once its running, it runs mint. Super responsive etc. Doesnt seem to run rich. Had a wee jam today. Seems to start ok with fuel pump switched on. Though this morning i still needed to turn off fuel pump to get it to start. Tis weird. Will check injectors etc. Though atleast i can get it to start every time now... Thanks guys. Quote Link to comment Share on other sites More sharing options...
sentra Posted October 8, 2012 Share Posted October 8, 2012 as per above, the injectors in these things are leakier than ?? they will definatly be rooooted. there is a magic bonus thing in the factory ecu to cut fuel for starting, cant remeber how it works, but you dont need a switch (possibly only in the s5 ecu?) Quote Link to comment Share on other sites More sharing options...
KIRK Posted October 8, 2012 Share Posted October 8, 2012 if its of any use i seem to remember(from when i read the entire internet about fc and looked at all the trademe auctions), it being pretty common for dudes to fit switches into series 4 to cure this problem. haha Quote Link to comment Share on other sites More sharing options...
Goat Posted October 8, 2012 Author Share Posted October 8, 2012 They are pretty high flow injectors eh? Spensive to buy new? Second hand ones would most likely be grott too eh.. Any other vehicles they can be pinched off? /will probably just run leaky for a bit and use switch to start it. Make sure the car doesnt fail cert or some other higher priority thing... hah Quote Link to comment Share on other sites More sharing options...
SHGWAG Posted October 8, 2012 Share Posted October 8, 2012 If I were you I'd get them checked at the least. Dodgy injector + turbo = Bang. Quote Link to comment Share on other sites More sharing options...
Poo Posted October 8, 2012 Share Posted October 8, 2012 My series four was an anus when it was cold. If I even thought of giving it a bit of welly and it wasnt up to temp it would flood. Cranking it over wouldnt help, but only drain the battery. A pair of vise grips on the fuel line would clear the rotors of fuel (first thing I could think of). I soon learn that the loom that runs underneith the steering colum could be pulled and it would kill the power to the fuel pump. This also cleared the flood. Quote Link to comment Share on other sites More sharing options...
fulloc Posted October 9, 2012 Share Posted October 9, 2012 Could it be as simple as fouled plugs? and also what is the compression like? I had an issue with my series 5 once where it randomly wouldnt start one day, i thought it was toast. i tried a few things but in the end took it to glen monroe (rotary power) he fooled around with a 1m long phillips right down over the back of the top mount (i was young/ wasnt watching) he adjusted a screw of some kind and it was good as new. Quote Link to comment Share on other sites More sharing options...
KIRK Posted October 9, 2012 Share Posted October 9, 2012 They are pretty high flow injectors eh? 550cc arnt they? they are expensive to buy used aswel haha. i think i sold mine for like 300. that might of been series 5 tho Quote Link to comment Share on other sites More sharing options...
Goat Posted October 9, 2012 Author Share Posted October 9, 2012 Compression is good as far as i know. Got the figures when i bought the engine. Cant remember them exactly, but was good enough for me to buy the engine. Over 100psi i think per pot. Engine seems to be pretty healthy. I'm sure its just leaking injectors/ecu not cutting fuel pump for cranking. Cos my god did it flood the shit out of itself when i first tried to start it. (Never before have i seen petrol dripping out of the exhaust manifold and pooling on the floor! Haha) I dont think its fowled plugs, as as soon as it catches (with fuel pump switched off) it purrs like a dream. Runs beautifully, no missing or surging or anything. Sounds like a healthy rotor!. Though i should wack some new plugs in it. As the condition of the old ones is unknown. Hah Cheers guys! Quote Link to comment Share on other sites More sharing options...
phtmbl Posted October 10, 2012 Share Posted October 10, 2012 as said above it is an ecu issue or leaky injectors, we would pop the bonnet and pull out the relay wind over to clear the fuel put relay in and it would start, if it is running fine when it does run dont bother with plugs spend the $$$ on testign injectors Quote Link to comment Share on other sites More sharing options...
0R10N Posted October 10, 2012 Share Posted October 10, 2012 They are pretty high flow injectors eh?Spensive to buy new? Second hand ones would most likely be grott too eh.. Any other vehicles they can be pinched off? any Denso top feed style injector should fit, just be sure to match the impedance with your existing ones. (Series 4 can come with either low or high impedance depending on build date) Mitsi Evo 550cc injectors are fairly commonplace. Only issue may be the plug shape, oval versus rectangle. injector testing/cleaning was $20 per injector last time I had it done. Quote Link to comment Share on other sites More sharing options...
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