Nothing has changed on my feedback after reading this. relays work or they dont, not just half assed. Poor ground or poor voltage will cause things to work sometimes and weak in nature.

 

Yea Im with you. Simply put, I dont know what just happened. I agree its probably from a poor ground or poor voltage but i feel i eliminated those two. I tried multiple ground locations in the trunk (even sanded the ground locations to expose bare metal) and checked the battery showing 12.2V when tested (14V when running). I checked all the connections under the dash, all the fuses, everything checked out. And I know I wasnt trippin maybe unable to hear it prime because i was in my garage and it was dead silent when i checked.

This is a long hard to follow read on what happened today so proceed at your own risk LOL:

I installed the new walbro450, car primed right away. Went out for a spin, dialed in my boost duty cycle to work through my other issue i was having (uploaded the map several times with adjusted boost duty cycle tables). Then returned home. Turned off the car. Turned the ignition back on then nothing. Took maybe 20 ignition-on's to get the pump to prime, started the car back up and it ran and idled okay. Turned the car back off and no prime upon ignition-on again. For over 20 cycles. Looked all over, took the fuel pump carrier back out rechecked the installation, checked all my relays made sure everything was tight and secured. Checked all the under dash fuel pump related fuses, scratched my butt, scratched my head, reuploaded the same map up to three times, all of a sudden i could hear the fuel pump priming but its soft and subtle...not the semi-violent strong vibrating prime that im used to (it used to sound like my fuel lines running under the car were vibrating). I hit "engine-start" and it would crank for about 10 times, I let off. Turn the ignition off and back on. I hear it subtly prime again. I hit "engine-start" again and after about 8cranks it will turn over in the slowest weirdest (like it doesnt want to turn over) way then eventually find idle rpm and idle and drive fine again. I drove it around, parked it, turned the car off. Turned the ignition back on, heard it prime soft, then hit the "engine-start" again and boom 2 cranks and it turns over! I repeated this about two or three more times with similar 2-3crank turnover starts. I then shut her down and called it a night. This was a weird ass night to say the least.

 

Mijae007 the weak point is the OEM connector on top of the fuel basket, it is not rated for the kind of power these high flow pumps need.
If you bypass this connection like junky did I'm sure your problems will go away as well.

 

As in the prongs at the top of the fuel basket aren't rated for the required power? Because I did rewire with the thicker gauge wires supplied by the SOS kit for both the power and ground going to the top of the connector that goes into the fuel basket port. I wonder if the connector/port inside the fuel basket where the pump wires go directly into the basket is also a weak point to consider...

Also to note, Im running the SOS fuel return kit which came supplied with a new fuel basket (not sure if its oem or aftermarket). Would boosted s2000's benefit from a modified or re-designed fuel basket? It seems a lot of people running aftermarket fuel pumps have priming issues based on all the older threads i've found on this issue. And i know a couple active members on s2ki have had problems with overheating and melting at the top of the basket connector site. But I'd hate to modify my fuel basket to run the wires directly to ground and power bypassing the connector, rather prefer to run the basket with the connector/port as it was intended. Maybe SOS will offer a new product if they are also made aware of this problem?

 

Thicker wires helps but those pins are trying to deliver more than double the stock current flow, at startup it's probably even more than that.
It doesn't take much of a bad connection there for the voltage drop being to high and then the pump isn't priming anymore.

 

Yep, and eliminate any other re pinning issue in that connector, which I had. Visually everything looked fine, but after the 3rd time I finally said F this and bypassed the whole equation and ran direct as mentioned.

Sorry its not the news OP may want to hear (drilling into his new basket) but its the only way to know 100% this is not where your likely issue is.

 

Thanks guys. I think we figured out where the priming problem lies. There are a lot of other threads pointing at the ground at the back of the head, faulty key, pgm-fi relay, bad ecu, fuses... but i guess another likely area is the fuel basket connector for those that upgraded their factory wires!

@s2000Junky its weird though, if and when i am able to get the car started it holds fuel pressure and runs fine even at wot holding a steady 12.5afr all the way through to redline. I'm worried this may suddenly change though if the power supply to the pump is inconsistent. I should measure the voltage at the connector during priming vs operational. I have a feeling maybe the walbro450 pump requires more voltage to prime vs when its just regularly operating hence the pump not priming consistently. It's probably losing some voltage at the connector site.

 

Yep be a good thing to check. Again, voltage/ inconstancies are normally not attributed to fuses and relays which either are completing the circuit or are not. And based on my experience, still pointing to the re pinned oem plug connection on basket.

 

Back again, same problem. Intermittent priming. Very inconsistent, sometimes takes 2 ignition-ons and sometimes takes over 20 ignition-ons for the pump to prime. I used a multimeter and everything checks out. The voltage located before and after the hanger at the connector reads 12V when ignition is turned on. The voltage going into and out of the relay also reads 12V when ignition is turned on. I tried multiple ground locations for the main ground as well as the little ground on the hanger, same intermittent priming. WTF could the problem be? Are walbro 450 pumps known to have these issues? My aem 320 primed violently every single time ignition was turned on. I only started having these problems after i switched over the the walbro.

The odd thing is if and when i am able to get the car started, the engine stays running and drives perfectly normal (probably because voltage to the pump is controlled by the ecu once running). It's only when ignition is turned on it will prime when it wants to. To make it even more odd is the pump is receiving 12V when priming but doesnt turn on all the time.

Could it be the pump requires an EXACT voltage to prime. Because my multimeter reads anywhere from 11.3-12.2V when priming at the pump. Maybe the pump requires an EXACT voltage or threshold to turn on??

 

Do you have a current clamp? Would be interesting to see how many amps you see when it's not priming.
The startup current on an electrical motor can be very high, if it only gets 11.3V then that might not be enough for it to start spinning.