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Rb25 In S13 Cranking But Not Starting

bwick240

By bwick240,
in General Automotive Discussion

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bwick240 Newbie

bwick240

Posted
Posted

Hey guys I've just about finished an rb25 swap in my friends s13 and now were stuck on something. The motor will crank/turn-over, but it wont start. It sounds like it has great compression but just isnt getting the vitals. I'm not sure if the ecu has power, which would explain everything, but I also dont hear the fuel pump even priming. There is a small blue plug on the lower harness that we could not match up to its pair, nor figure out what it is. I will go over all of the grounds again just to make sure but I'm almost positive that those are correct. Any help is appreciated, thanks guys, I've already used a ton of info from this site and it has been extremely useful.

TRB-001 Rising Star

TRB-001

Posted
Posted

altho by the sounds of it uv got some sort of electrical problem, the most common thing iv seen done by people doing conversions at home is put the fuel lines on the fuel rail the wrong way.... make sure the one with the fuel filter DOES NOT connect to the fuel rail end with the pressure reg....

as for ur problem, i would be tracking down the a wiring diagram and check all your powers to a the ecu, especiialy ignition wiring,

make sure he doesnt have an alarm or kill switch he forgot to tell u about.

bwick240 Newbie

bwick240

Posted
  • Author
Posted

we checked the fuel lines and they were wrong... hah my bad. we have the ecu power and ground skipping the relay and going to direct power and direct ground. were getting 12v at the ecu with a meter so we know its getting power. after trying to start it with the fuel lines going the correct way is still does the same thing, cranks, sounds good, but doesnt spudder or hicup or anything. just keeps cranking and thats about it. I guess the next thing would be to check spark... how much is the ignition tied into the coilpacks? Were about to go over the ignition wires again to bring them to a solid connection instead of trying to go through plugs and relays. Thanks for the response, so far so good!

TRB-001 Rising Star

TRB-001

Posted
Posted

ur ecu needs to be switched on to start with (so it should be getting 12v from the ign switch) then it looks for a ign signal from the Cam angle sensor.... if there is no signal from that (which is another thing to check) then the ecu will not fire the coilpacks.....

as u said, check if its getting spark, if it isnt, check the CAS circuit and the power for the ecu from ignition...

also wot ecu u using?

bwick240 Newbie

bwick240

Posted
  • Author
Posted

the ecu that we are using is just a stock rb25 5spd ecu. the ecu is also getting 12v to the power ports on the plug. and the fuel pump is also getting power now because it primes right before the car starts. when i reversed the fuel lines after trying to start it a couple times with them backwards, i did have fuel pressure built up in one of the hoses. so i know im getting fuel to the rail. i havent checked spark yet but that will be done tomorrow or the following day when i get the time. I'll check the ign power with a meter and the CAS. thanks for the help, ill keep you posted.

RB_240_420 Apprentice

RB_240_420

Posted
Posted

I am said friend putting the RB25 into my 240. I am currently re-doing the timing belt to see if this motor will crank...

As i was doing this my CAS bracket decided to break in half for no reason... it fell off while i was looking at the belt. Does anyone know where i can order a new bracket

TRB-001 Rising Star

TRB-001

Posted
Posted

nissan will have a new one, but ur better off getting one from someone on here in the forsale section

if its backfiring or poping thru the air filter then ur timing is out....

either the timing belt is out a tooth (or so) or the CAS is out (or faulty)

check that the 3 timing marks line up

  • 4 months later...
offtap87 Explorer

offtap87

Posted
Posted

i am having the exact same problem, got spark and fuel, the timing marks all line up, put a screw driver on the piston when checking TDC the timing seems to look fine, the only weird thing is the normal position that the plug on the CAS sits at is no where near where it should be the plug and wires have to stretch right over turning the CAS clockwise 180 deg, when the cam timing marks are lined up which mark on the harmonic balancer should line up with the timing cover mark? my timing cover mark is pointing just right of the last timing mark on the balancer, thats if u spin it clockwise its the last mark.

offtap87 Explorer

offtap87

Posted
Posted

sorry for bringing up old thread but i am having the exact same problem, got spark and fuel, the timing marks all line up, put a screw driver on the piston when checking TDC the timing seems to look fine, the only weird thing is the normal position that the plug on the CAS sits at is no where near where it should be the plug and wires have to stretch right over turning the CAS clockwise 180 deg, when the cam timing marks are lined up which mark on the harmonic balancer should line up with the timing cover mark? my timing cover mark is pointing just right of the last timing mark on the balancer, thats if u spin it clockwise its the last mark.

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