DaleClark

iTrader: (55)

Something is crazy wrong if you see 6v at the pump. The pump is designed to switch between 9v for low load/idle and 12v for load conditions.

This mod is really best suited for cars with stock to mild fuel pump setups. If you are going for a dual pump or big fuel pump setup for big power you're far beyond this simple re-wire. It's not hard - fuel pump need a certain amount of amps, and the bigger the pump and the bigger the load on that pump the more amps it needs, the wiring needs to support it.

Dale

speedjunkie

iTrader: (3)

Has anyone else had issues with the car being difficult to start after doing this mod?

I just got the car back together after doing numerous things, and I'm having issues with the battery voltage dropping hard during start up. I thought maybe my battery was bad because the voltage was dropping to 10v while cranking, so I replaced it with an Anti-gravity ATX30, and I replaced the alternator just in case (I had just rebuilt one but I had some questions about it). I had taken the old battery and alternator to several different auto parts stores and they all said they tested good. The new alternator is putting out about 14v whereas the one I rebuilt was only putting out around 13.5v. The new battery is dropping to about 11.1v while cranking and wouldn't start the car by itself, so I replaced the alternator too and it started up after that but struggled and still dropped to 11.1v. After running the car a few minutes I shut it off and tried again and it fired up on it's own. I tried again about 30 minutes later and it started again.

I have the battery on a circuit breaker that I always disconnect for the night, but I do have a wire going to the stereo and one going to a phone charger that are hooked directly to the battery and not through the CB. I opened the CB and left the battery tender unplugged all night and tried this morning and it wouldn't start on its own but did after I put it on the tender. I ran the car for a bit this morning and after I shut off the car the battery tender said the battery was at 14.2v, but it steadily dropped to 13.8v over about 30 minutes and that's with the battery disconnected. I put my phone on the charger and it dropped to 13.6 within a few minutes and I pulled the two fuses for the two wires that are constantly run off the battery and it's been holding at 13.6v, but not increasing. So I'm not sure if maybe the battery or the tender are keeping it from holding a charge more than 13.5ish (the old battery wouldn't go above 13.4v). I don't see how the battery voltage would drop when there is no possible way for there to be a drain on the battery (after disconnecting all the wiring).

Either way, with the voltage dropping so much on cranking, I was wondering if it was related to the wiring changes I made over the winter. This isn't the only change I made, but my buddy has a similar issue and he did this mod as well, so I wanted to check with you guys to see if anyone else had the issue too or I should start looking elsewhere.

scotty305

iTrader: (2)

I didn't notice anything different, and I changed nothing else when doing this mod on my car. Does your engine sound like it's cranking slowly, like the starter isn't getting as much energy? If it still spins over quickly, I would look elsewhere like the ECU's fuel settings or Idle Air Control Valve settings (which controls airflow), or swap new spark plugs in case the old ones are fouled from idling or cruising with too rich of a mixture.

DaleClark

iTrader: (55)

Alternator doesn't effect cranking. Is your battery relocated? 9 times out of 10 battery relocations have tons of electrical issues. There are some recent threads on the topic.

Could also be your starter is getting weak.

Typically a battery at rest is like 12.5v or so, that's a healthy battery ready to start a car.

Dale

speedjunkie

iTrader: (3)

No it still cranks fast. I replaced the starter internals with RX-8 internals a few years ago and it's still doing well. The spark plugs are brand new also and I'm just getting the car back on the road. But I think we traced it to the ECU relays (aftermarket ECU).

Yeah I've had it relocated for several years now with no issue and no issue right before doing this winter's work, so it's something I did this winter. I figured the alternator wasn't charging it enough when I drove it very shortly last weekend and it left me stranded at the gas station. And this new alternator does charge a bit better. However, one of the ECU relays is only getting 6v at times and after we pull the relay and put it back in it will get 12v and the car will start normally. Swapping the relay with another makes no change. So I have to talk to Chris Ludwig about how he wired the relays so I can trace it more easily and I no longer think it has anything to do with this mod.

Thanks guys!

simronrx7

iTrader: (8)

Will this make the car throw the error code 51?
“error code 51 Fuel Pump Relay, Speed - open or short circuit”


car runs and drives but still has the 3k fuel hesitation issue.

simronrx7

iTrader: (8)

Just wondering if anyone else got the error code 51 after performing this mod? I know I connected the right wires, please help.

speedjunkie

iTrader: (3)

I never had that issue with mine. Although I was still using it to trigger the fuel pump relay off the battery, but I switched back to this way. I haven't started the car yet. Oh, but I don't have stock gauges or stock ECU anymore, so I doubt I'd get the same code.