Purchased this system with a crate motor a while back. I have a 383 stroker in a C2. The Massflo/ProM racing guys have been no help. I have checked everything I can think of. The system is flooding the engine . Fouled plugs, cannot breath in garage etc. I have used 2 computers, changed plugs and O2 sensors' changed BAP sensor. When I back off regulator pressure to zero this seams to help but still have too rich of a mixture. If any body is familiar with this system or this problem in general , I could really use some advice.

 

It sounds like whoever previously owned the EFI system tried to tune it for either a larger displacement or more horsepower and missed the mark completely. (Just a guess, but since you're flooding the engine, either the injectors are too large, the fuel pressure too high, or the pulse width is too long.)

You're best bet is to work with Mass-Flo EFI (although you said they weren't much help). You really need to start out with a stock, factory tune in one of your computers so MassFlo has some idea of what parameters you're using and can work with you from there. (They don't do tunes. That's not their business expertise.)

They should be willing to work with you to see if any of their products are at fault, but that's about it. They may be able to recommend a tuner in your area that can get the EFI engine running correctly using their tuning software.

If you're not familiar with their software and/or the parameters that can be modified, definitely seek the help for a knowledgeable tuner as there are many ways to screw up an EFI tune without realizing it until you try to start the engine.

I know this isn't much help for the immediate problem, but I would definitely get some professional help with the tune. Good luck!

 

Sorry, didn't mention the system was purchased new with the motor and tuned with a Moates F3 chip. At first start up ran fine, then the trouble began. After confirming my installation was correct with Chris at Massflo/ProM he had mentioned that they had a problem with the engine builder damaging the computers and suggested I find a good used Ford A9L computer, plug in the chip and go. I would assume the correct injectors have been provided. It will run better, or not as rich if I back off the regulator to zero. What would affect the pulse width? Runs rich regardless of which computer is used, with or with out the chip. I have replaced the O2 sensors and spark plugs have been cleaned or replaced after each attempt,as you can guess they are sooty black. I had initially contacted ProM as mentioned but after a couple phone messages and numerous emails to both Chris and Sean with no results I have given up on them being any help. Any tips would help.

 

Just trying to get some background info:

1) Was the engine purchased with the Mass-Flow EFI installed, or did you purchase the EFI system separately? Is this the Mass-Flow EFI system you have installed?

2) Who did the initial tune that included the Moates chip? (Is the Moates chip part of the Mass-Flow EFI system purchased, or an after market item?)

3) What was the targeted HP of the 383? (The HP target determines the flow rate of the injector to be used.) Do you know the flow rate of the injectors installed?

4) When you stated that the initial start-up run well before all the trouble started, did this happen before or after the tune?

5) I understand that the overly rich condition deceases in intensity when you turn down the fuel pressure regulator. What has me confused is "zero" pressure would mean no fuel flow within the rails. What is the fuel pressure supplied directly to the fuel rails from the fuel pump? (Fuel pressure greatly influences the amount of fuel an injector flows.)

It's not impossible that two computers could be bad; however, if the Moates chip is not part of the factory Mass-Flow EFI system, I would use the Mass-Flow chip first. (The chip contains the fuel map which in turn used to select the correct pulse width for the injectors. Getting the fuel map wrong causes all sorts of problems.)

If you can find out the answers to the questions above, it would be easier to help you troubleshoot the EFI system.

 

Thanks for the help. Once car is fully together I plan taking to a reputable tuner. Is still very much a work in progress

 

Thanks for the responses. I've addressed each question individually below to keep this thread from growing too large to be of help.

 

"2) Who did the initial tune that included the Moates chip? (Is the Moates chip part of the Mass-Flow EFI system purchased, or an after market item?)
The builder provided the engine specs to massflo who I assume did the initial set up. It was explained to me that the moates chip was a base tune and that the system would learn."

Since the Moates chip was part of the original configuration, I'd go ahead and use it. (I've personally had nothing but good experiences with Moates chips.) I'm assuming that the Moates F3 chip was installed when Mass-Flow checked out your system's computer and replaced the power supply. If not, please let me know because the fuel map is located on the chip, and that needs to be verified. (Most of the times, chips simply burn out due to a short circuit, but it's possible that a discharge of static electricity could have altered the chip's tune.)

 

"3) What was the targeted HP of the 383? (The HP target determines the flow rate of the injector to be used.) Do you know the flow rate of the injectors installed?
The engine dyno'ed at 446 HP, + 6hp from advertised. The build sheet is hard to read. Can I tell by looking at the injector?"

If the engine was targeted for roughly 440 HP, I'm guessing that the installed injectors are 36 LB/HR units based upon the RC engineering Fuel Injector worksheet.

I used 0.50 for the BSFC, 0.80% duty cycle, and 43.5 PSI (3 BAR) for the fuel pressure to calculate a 34.57 LB/HR (363 CC/MIN) injector. I rounded up to 36 LB/HR since that is a common injector.

If you can read the part # on the side of the injector and give me the color of the injector top, we should be able to determine what size injector is installed.

For example, my '89 Vette uses a Ford Blue Top F55E-A2E rated 262 cc/min (25 lb/hr) @ 43.5 psi (3 bar), resistance 14.4.ohms:




Here's and example.

 

"5) I understand that the overly rich condition deceases in intensity when you turn down the fuel pressure regulator. What has me confused is "zero" pressure would mean no fuel flow within the rails. What is the fuel pressure supplied directly to the fuel rails from the fuel pump? (Fuel pressure greatly influences the amount of fuel an injector flows.)
I just meant zero at the regulator, the fuel pump was free flowing. Wahlbro pump in a Rick's tank"

This part still has me confused. The Wahlbro pump is probably this one rated at 255 liters per hour at 43.5 PSI. Knowing what fuel system pressure the injectors are seeing is important because although the injector's flow may be rated at 43.5 PSI, it will flow way more at 50 PSI. What does zero on your regulator mean in terms of actual fuel pressure?

For example: My '89's Vette's fuel rail pressure after the regulator at WOT is 35.5 PSI because I have a larger than stock injector installed. The stock injectors used a post-regulator fuel pressure of 43.5 PSI at WOT. (BTW the idle fuel pressure is always less than WOT.)

Is there any way that you can measure your fuel pressure to the fuel rails? (This would be the #1 source of your overly rich condition in my experience.)

 

[I]Massflo did not check out the computer, would have liked to have had them perform this work but they had already gone "dark" on me at this point I had initially thought that the chip could be bad. I used each computer both with and without the chip and had the same bad performance.

 

The PN is 01D114B which looks to be a Racetronix injector rated at 40lbs.

 

I am a little confused here myself. That is the pump I am using. Now the pump really doesn't create pressure, only volume. The regulator creates the pressure. Am I correct? I can check the pressure at the inlet connection to the fuel rails this weekend. Shouldn't the pressure be what the regulator is set at? If it is higher what then?
I cannot thank you enough for this help

 

Based upon the other info you have provided in the other two responses, I think that the source of the problem is not with either computer nor either of the chips. I believe that your fuel pressure is the culprit.

Just be sure to document what has and has not been checked out when you finally take the Vette to a tuner when we get it running.

 

I did a quick check on the Racetronix 01D114B injector. According to their site, this injector series is rated at 37 LB/HR which would be in line with the original HP estimate for the engine. (I thought that it would be around a 36 LB/HR injector given the minimum injector needed to flow at least 34.57 LB/HR.)

Was there something in the engine's dyno sheet/documentation that indicated this was a 40 LB/HR injector? Just curious. Thanks!

 

First off, you're correct that a pump's capacity is measured in flow not pressure. I may have thrown you a curve ball when I mentioned that the Wahlbro pumps was rated at 255 lph at 43.5 psi. I combined apples (pump flow) with oranges (injector flow at a rated psi). Sorry about that!

The regulator should be set such that a WOT, the injectors are receiving fuel at their rated psi which in this case is 43.5 or 3 Bar(ometic pressures). The system will simply by-pass any fuel that cannot be used.

I think that the problem that you're experiencing is related to too high a fuel pressure at the injectors. Raising the fuel pressure above that at which the injector's rated pressure will make the injector flow more fuel than advertised. (Most of the adjustable fuel pressure regulators are designed to crank up the pressure to allow more flow.)

I don't know for sure what type of fuel pressure regulator is installed on your system, but given the fact that it's aftermarket and a bolt-on to large and regular displacement SBC's, I'm guessing that it's adjustable. Some use thumb screws to increase/decrease the pressure. Other use a fixed slot with three or four setting options for the same function. The original GM were preset and used engine vacuum (or it's absence) to increase the fuel pressure.

Taking a fuel rail pressure reading would at least be a start in the right direction. It could be that the regulator isn't functioning properly because as you said turning it down to zero improves, but doesn't resolve the situation. Given the high flow characteristics of the Wahlbro pump, the injector might be seeing 60 psi of unregulated flow rather than the 43.5 psi they were designed for.

Glad to help. I remember trying to troubleshoot the early TPI systems on Corvettes in the early 80's w/o a factory manual. We had plenty of items to fiddled with due to aftermarket companies like TPIS and others, but hadn't a clue to how things really worked! Been there, done that.

 

This is the current fuel pressure regulator offered on the MassPro EFI systems today. Is it the same as that installed on your system?

If so, you can download the installation/adjustment instruction sheet here. This unit uses an engine vacuum port to decrease the fuel pressure for idle, cruise, and low rpm operations. It is important that the engine vacuum port be connected for street operation. The typical installation would take engine vacuum from the same location that supplied engine vacuum to the power brakes booster. It's important enough to check to ensure that this port is receiving engine vacuum while the engine is running. (Wouldn't be the first time that a one-way, anti-backfire check valve was installed backwards killing the vacuum to the port.)

If this isn't the unit that you have, if you could provide any info on the fuel pressure regulator that you do have, it would be helpful as well as a description of what steps you take to adjust the fuel pressure on the unit.

I really think that too high a fuel pressure is what's causing all the problems you're experiencing.

 

Yes, this is the regulator I am using. To set I followed the instructions in the massflo set up instructions. Set to 40lbs with vacuum plugged. I took the regulator apart to see if their was any problem with it, they are pretty basic, diaphram was fine. I just recieved a an male to female fitting for use with a fuel pressure tester. The plumbing from and back to the tank is exactly as shown by Massflo. As I have mentioned before when I back off the set screw to reduce the pressure shown on the regulator the engine does run much better. Will let you know what pressure I come up with at the line from the tank to the fuel rails. if the reg. is set at 40lbs I would assume I would get the same reading. If not then what?

 

I just googled the PN , probably just got bad info

 

Or it could be that MassFlow EFI's recommended fuel rail pressure (40 psi) got inadvertently branded as the injector's LB/HR figure. Either way, we at least now know that the injectors are rated 37 LB/HR.

 

Actually, there are two items that need to be verified:

1) What is the current fuel rail/regulator pressure with the vacuum port disconnected? This should be 40 psi according to the info from MassFlow EFI. (BTW, since your injectors are rated at 37 LB/HR at 43.5 psi, they will flow roughly 35.45 LB/HR at 40 psi which is closer to the calculated 34.57 LB/HR needed for 440 HP.)

2) Does the vacuum port work by lowing the fuel rail/regulator pressure when the engine is running. Need to check two things - ensure the port receives an engine vacuum signal at idle and that the vacuum signal is strong enough to allow the regulator to reduce the fuel pressure below 40 psi.

I think that item #2 is the critical pass/fail item. You can always reset the fuel pressure to a lower than recommended 40 psi to get the engine at least running; however, to have a streetable ride, the vacuum compensator must be working properly. I would trace the source of the engine vacuum to make sure the vacuum reading that you see at the source is the same that you see at the regulator.

Again, over the years I've seen all sorts of problems come into the shop from split hoses to check-valves installed backwards. Perhaps the most common mistake I've seen on carburetored Vettes is using ported vacuum (above the throttle blades) used instead of engine vacuum (below the throttle blades). Good luck!