joefish1298

Normally when I turn the ignition on, I will hear the fuel pump prime, wait for it to finish and then start the car. However, I would say one out of ten times, when I turn the ignition on, the fuel pump doesn't prime. If this happens, I switch the ignition off and back on again and the pump will prime. The fuel pump has never not primed twice in a row.

I'm running the AEM series two and was wondering if anyone else has encountered this problem which would indicate a bug/problem with the AEM, or whether this is unique to my car and I have some other kind of electrical gremlin.

Thanks.

RolanTHUNDER

Bump. I'm wondering about this now as well since I'm on AEM Series 2 ECU and AEM 340LPH pump. Does the ECU need to be calibrated with the AEM pump?

EOE

Bigger or more efficient pump can alter your fuel pressure and you might need to rework your fuel map. I wouldn’t expect anything drastic but definitely something to keep an eye on.

If you have a fuel pressure sensor and AEM Infinity like capable ECU it can automatically correct for the fuel PSI variation... or save your engine when pump dies under WOT hehe.

yamahaSHO

My AEM v2 will prime the first time I turn on the ignition, but if the car has sat for awhile, I hold the throttle down to crank for oil pressure. The only way to get it to prime after that is to turn it all the way off and wait a couple of seconds.

RolanTHUNDER

Hey thanks for the reply Tuned on AEM Series 2
So I noticed idle suddenly go quite rich during cold starts in particular immediately after the pump upgrade. During normal driving the AFR fluctuates quite a lot compared to on stock pump and today I noticed VTEC go on then off then on again at 6 grand then 8 grand. I backed off and went to look at tuning but I can't adjust as I don't know what exactly to do lol. Oil level is good, no strange material in the VTEC screen but my solenoid does leak oil thru the pressure switch even though I replaced the o ring. MAP sensor is OEM but I replaced it with my spare just in case of the map whack thing acting up. Haven't test drove since. Waiting on my tuner to remote in and make a few adjustments.

I shortened pump prime time from 6 to 4. It primed way too long I reckon lol.

RolanTHUNDER

I noticed this as well but figured it was due to a bad battery which was over 3 years old. I replaced the battery with a new stronger one and now after the initial loud prime and say I drive to a gas station, I switch off, fill up then switch ignition on from ACC, I'll hear a soft prime, push start and she fires right up. Previously on the bad battery in the exact same scenario it did not start! I had to turn the key all the way off like you then back on and it primed then started.

yamahaSHO

I've got a new Lithium battery, so that's not my cause. When mine primes, it's all the same. It's not getting told to prime unless I turn the ignition all the way off and back on.

RolanTHUNDER

No that's odd. It should prime whenever you turn the ignition on and not only do so when you turn the key all the way off. I don't even think there's a setting in the tuner software to make this option active or not.

yamahaSHO

There isn't a setting in AEM Tuner, but that's what mine has always done when I hold the throttle down to build oil pressure before starting. Try that and tell me what yours does.


BTW, turning the ignition all the way off leads to then turning on the ignition (that's one of the criteria you just mentioned. )

RolanTHUNDER

Thought so. Um, ok maybe I will try your throttle hold down before starting technique

Ignition all the way off, meaning key turned all the way off or just to ACC...