Car is setup right now with a batt charger box and the pump jumpered on and Efi Live logging.....20 min eta.

 

ZERO fuel pressure drop.....WTF......only other thing would be voltage to the right right? I did notice as soon as power is removed the fuel pressure drops to 13. Do Walbros have an in pump check valve?

 

Yep, got to fixture a gauge to supply line to get dead head pressure when pump is hot. Anywhere on the line is fine. Wherever easiest. Have to decide which is easier, define test and get data to make informed decision or swap parts and see what happens. Sometimes swapping a part is easier, especially on an intermittent issue. Good luck. You'll get it sorted out.

 

No pressure drop from pump through regulator? I suspect reg diaphragm heating up and not holding pressure. Reg in engine bay?

 

All Walbros have a built in check valve.

So a drop to 13psi does seem unusual. Of course...not all regulators seem to hold pressure after shutdown either, so you'd need to inspect to see which might be suspect there.

Maybe try taking the FPR apart to see if anything looks odd ? I know one guy here in the UK who hates Aeromotive stuff as he got a batch of bad regs with swarf in the return seat inside the reg.

So the static test sort of proves pump/reg are capable of maintaining that pressure over 20 mins...on the road, would pressure have dropped by that stage ?
No other anomalies like battery voltage or anything dropping ?

I'd doubt the reg diaphragm is an issue. They're such a simple item, they either work and hold pressure/vac etc, or they leak which would be obvious too. Inspection is easy though.

 

I'm measuring fuel pressure with a transducer on the end of the shraeder valve on the fuel rail. Logging through custom pid that uses EGR pintle position to efi live so no eyeball stuff. I haven't measured the drop through the FPR but if it's dead nuts on over 20 min running no engine it seems reasonable to rule out the FPR.

Racetronix FPR is mounted on the backside of the rear seats in the Camaro, no engine bay heat. It's by the cold side piping from the turbo (rear mount) but can't imagine that would do anything. I could insulate the cold side pipe just to be sure but seems like a long shot.

I've logged battery voltage and haven't seen issues but maybe I need to get a meter on the power at the pump from the start of a drive to the end and see if it's dropping. Ive got a dedicated 16AWG wire from the alternator through a fuse/relay so unless the alternator is taking a crap, seems unlikely.

Only so many things it could be though lol.....ANOTHER THOUGHT......what if the turbo is actually heating up the fuel? I've got a blanket on the turbine but, it's a thought.

 

Again, I would doubt fuel temp is the issue.

Simple test would be when fuel pressure is verifiably at its worst...refill with fresh fuel.

Or as said, log fuel temperature and see

 

I need to see if I can find a k couple and slid it into the tank when fuel pressure is down and get a reading. That and battery at the rail are the 2 things to check. So odd to still be fighting fuel pressure issues on a basic setup.

 

Stick an adapter somewhere on the rails or line to the rails and chuck a sensor in.

Your regular coolant temp sensor would do fine....and if you were happy driving the car with that unplugged for a bit and plugged into a sensor monitoring fuel temp instead....job done.

 

Time to scavenge the garage

 

Very well could be the turbo heating up the fuel. You could also let it idle for a while and just let the heat rise to the tank.

 

Guessing it won't be the same as after the cars been driven and made pulls. Lot of heat from that thing after a 2-3 gear pull lol. I could let it idle though to rule out a battery voltage drop after it's warm.

 

Should also be a lot of airflow under the car when driving.

 

Just datalog to see what voltages are doing

 

The pid to scan would be ecm voltage.
But that doesn't tell you voltage at pump but gives a good idea.
Buying off amazon for fuel pumps is also hit and miss. Reviews...meh. People will justify nearly any issue as long as the pump is cheap. The knock offs look so similar you cant tell.
I have had 3 customers doing remote tunes and i tell them add the ECM V parameter and its like 11.xx or itll be 12.xx then 11.xx above 3k rpm and get worse. These pumps are made for 13.5v and most 4xx pumps need at least 22 amps. You cant measure the amps of course but volts gives you a good idea. They all upgraded the pigtail and went to a better alternator either truck 140/160 or powermaster or mechman etc and then we had to retune the whole thing because the trims were obviously all over the place. The vex maf, and pe all looked way better after that also.
Voltage and current at the pump is important. Thats why the 99-02 kits come with the upgraded bulkhead also. anything less than 13.5 is going to give diminished capacity.

Also, not all wabros have check valves. Quite a few dox but not all. So dont rely on that. Also dont rely on just because it says walbro on it that its a walbro pump. Im not saying buy from us or only racetronix, but know your seller. Be able to call/email them and talk to them. That pays off in the long run.

If youre looking for a great pump that will put in the work easily and keep your bucket full, try the 340 with venturi we have. Thats not a product plug, its a great option that will use all of your parts you have now unless you cut, spliced, and drilled of course. Also make sure to direct the return fuel from the missing regulator assy back into the module with some tubing or line or whatever.

 

It's a piece of **** to measure pump current and log it if need be.

Just stick a current clamp on the supply to it, or link a current clamp to a scope or the ecu.

And a 450 does not draw 22A under any normal usage. I tested mine and they only pull about 13-14A at 60psi ( each ). If you were to ramp that up to maybe 100-120psi they might get into the 20A range, but when most of their pressure release valves start to operate before that.....it just aint gona happen anyway.
No doubt the 500+ pumps will pull more than the 450 though.

Whether that current changes on ethanol, I do not know as have not tested that yet. But given the fuel is thicker, it is possible. I will be trying a 50/50 mix at some point, so will check current when I do. But on regular fuel, they arent pulling massive amounts ( relatively speaking )

 

I have access to equipment to measure current, just don't think that's going to be my smoking gun. Ecm voltage is a good pid, I was only aware of the battery volts pid. Like I said, measuring the voltage at the pump is on the to do list. That and cruising around for awhile no boost. That should tell me if A) voltage is dropping over time as I do have gauges and an oil pump, wideband, larger fuel pump, etc all sucking battery, and B) if the pressure doesn't drop while just cruising then I can make some pulls and see if it drops indicating heat from the turbo is a contributor.

 

45 min cruise no boost and the battery voltage didnt move more than a few tenths of a volt (13.5 down to 13.1) and fuel pressure didn't change more than 2-3 PSI. That said, cruise is going to charge the battery better than idle so a lot of stop and go traffic may drop the battery voltage more which would drop fuel pressure. Maybe it's time for a new alternator.

 

There have been more than a few posts of people with alternators that simply stopped charging at higher rpm.

I had the same many years ago. An alternator that had been on the car for years and repaired once.....failed again. And I had the same place repair it. However, after they did, at exactly 6k, it would stop charging.

I bought another unit to try...and it was the same.

Eventually bought a better unit as was pissed off replacing them and ******* about and it's been good since. But there have been a lot of threads with similar issues, but you'd see the volt drop on a log, and of course fuel pump performance will suffer

 

I don't have logs but I do have video (form of log, I guess) of my voltage dropping 2-3 volts at WOT. I will be upgrading once it get my new motor built.