So how would YOU flowtest your injectors? I have a plan and I won't tell you it until I get some other ideas.
The one catch; Injector pod (TBI) stays near the car so I can use the cars fuel pump.

 

I want to do the same with the CrossFire injectors; here was my original idea (since I had an extra pump laying around.)

Get a gas can that I can stick the spare pump in.. run fuel lines up to a spare TBI (just the fuel metering setup.) Put two graduated cylinders up under each injector, somehow use sealant (clear silicone?) around the top of the graduated cylinder so you didn't get any evaporation (can you say boom?) leakage.

Somewhere I remember there being a computer program that pulsed the parallel port identical to the output of an ECM, and some simple high-load transistors that would run the injectors themselves. I want to say the article is floating around the 'net still; I might even have a copy in all of my stuff.

 

the the Tbi cars have a flexable line at the front of the engine bay, undo the hard line hold downs and unbolt the TBi swing it to the front of the can and place to messuring items under each opening. Make a program just fires the injectors at what ever constant and then see what comes out over a given time. Or maybie I'm just insane.

 

Not easy. Many years ago I had the same idea to flow test the TBI injectors. After I set everything up and turned on an injector, whoa, Houston we have a problem.

The spray emanating from a TBI injector is a fog. In the open this fog just up and disappeared into vapor. It would be difficult to contain it. Can't seal it into a container as the fuel into the container would force air/vapor out.

Maybe a chiller to help condensate the fuel would help.

At the time the only answer I got that made sense was to measure the fuel consumed from the feed tank. Prime the system, turn on the injector for a minute, or five minutes (waste the sprayed fuel), then measure the drop in fuel from the feed tank.

RBob.

 

OK, how bout this. Once you get the injectors into a comfortable area(swinging out from the flex lines sound good, spray the injectors into a small tube(something clear, and fuel safe.) but not just any tube. Plumb this tube to the bottom of a container that already has fuel in it, and you set up the graduation at zero. The top of the container has a very small opening, so very little vapor can escape, but enough to allow displaced air out(charcoal filter on top would be nice too). You'll shoot fuel into the tube, where it will dribble down to the tank, and raise the total level of fuel in the tank. take a good measuerment of before and after, calculate the volume, and repeat for other injector.

couple of issues to work out:
good seal on the bottom of the injector(make some sort of funnel to the tube, that has an o ring seal, and clips on(think master cylinder lid on older cars)

keep the fuel in liquid form in the measurement vessel(ice?) keeps vapor pressure lower, less fuel escape.

keep injector higher than level of fuel in container, otherwise, you start a siphon.Hmm..maybe moving it to the end, removing all the air in the tube might provide better results

keep injector at constant position while running the test, as that will move you zero point if you move it around.(up or down)

I dunno...whaddya think?

 

some glad wrap over the top of the tbi and some long vent tubes bent at a few angles

 

We have spare throttle bodies, with either an adjustable internal regulator or use an external regulator for fuel pressure, a bench with a fuel pump, a container of test fluid (not gasoline), an ECU, and a simulator (for a reference pulse to the ECU, and the ECU to allow any commanded pulsewidth, and to read the frequency with the laptop). Measure at several different duty cycles at the same frequency, calculate 100% flow rate, and can turn the PW down to find the min on time for accurate flow or where it stops flowing altogether, and if you draw a line between the flow at two different duty cycles, you can find the difference between the turn on time and turn off time at the axis intercept. Can get a lot of useful information from it.

 

DIY-EFI.org had an article about a DIY flow Bench.

IMO, for the few bucks they charge, getting a Pro to do it seems cost effective. To do it accurately, takes time, effort, and risk of fire.

 

Ah yes, risk of fire.... I've been known to have a few fires here and there. I like the challenge . Now that dyno fire where the rod spun through the block cutting the main oil galley spewing oil over cherry red headers... that wasn't my fault. That was the machine shops fault for cutting more than they said off the head surface . Nothing like pistons hitting the combustion chamber in a few spots to fatigue an already weak (but lightweight) connecting rod. :shrug:

I'll probably get a pro to do it if I didn't think one of the injectors was bad. One is firing a nice cone, the other looks like the old Holley Mopar injectors... chaos of streaming fuel. I checked my spark plugs and there doesn't seem to be an issue so I'm going to try flowing the injectors myself. I figure I'll just use a digital scale to measure the fuel flow rate. This is what I did when I tested a bunch of fuel pumps.
Thanks for the suggestions guys and if you find any of those articles please let me know.

 

There was a thread here about this, or more about static injectors, and how they act erratic just before static, yada, yada.... In that thread was mentioned a lab-type setup for flowing injectors. I'm gonna hit and see what I come up with....

 

Isnt there a non-flammable fluid with a similar viscosity to gasoline? I wanted to do the same thing but the possibility of fire part doesnt appeal to me.

 

Mineral Spirits. Still flammable but not like gasoline. Problem with gasoline is the compunds such as propane and butane that quickly evaporate.

RBob.

 

Definately either bad or dirty. Can try back flushing it to see if that clears it up.

RBob.

 

You can measure the oposite.

Put a scale under the 'fuel tank' and measure the weight reduction.

 

I don't have another fuel pump. So I have to use the intank fuel supply.

 

I'm hoping thats the only trouble with it.
Maybe it's time to use BBC injectors.

 

Forget the fuel pump. Use air pressure. Get ahold of a 5 gallon air tank, fill it up at a gas station or local shop, and put an adjustable regulator on the output. Set the regulator for your test pressure. Hook the regulator output to a short air hose. Cut the other end off the hose so you can seal it to a graduated cylinder with a double hose clamp, and plumb the bottom of the cylinder to the injector feed line (use more air hose if you don't care about durability or high-pressure fuel hose if you do.) Plug/clamp the fuel return line. Fill the cylinder to the brim with your fluid of choice, hook your hose up, open the tank valve to create "fuel pressure" and cycle the injector enough to bleed the air out. Note the zero point of the cylinder, run the test cycle (let it squirt into a bucket or whatever,) and the rest is just math.

This way you can also take it entirely off the car so that if you DO use gas and you DO start a fire you won't have to have the hood repainted.

 

Have you done that?.
Interesting......

BTW, if one uses items like Stoddard Solvent, remember there are bacteria that can live in that soup, so if you have any open cuts wear gloves.

 

No I haven't done it, it just seemed like a good idea. Air tanks are easy to borrow (and not too expensive to buy,) and you can get an adjustable regulator from most parts stores for under $15.

The biggest thing is having the grad. cylinder on the pressure side. By measuring the volume lost on the pressure side, you eliminate any errors due to evaporation or atomization after the injector. You can't do this with a fuel pump...you need some other fluid to replace the fuel so you can see the difference. Air is a natural solution.



edit: The biggest trick will be finding a balance between the injector cycle time and the volume of the grad. cylinder. It may take a few runs to get it right (enough cycle time to get a good measurement, but not so much that you run the cyl. out of fluid,) and if you don't have a compressor then getting more air could be a bit of trouble. Lucky for me I have a compressor.

 

OMIGOSH, I never knew that! I use the stuff all the time, and FORTUNATELY, I wear latex gloves all day long anyway.....

Jon, sending you a PM about a fuel pump.....

 

I would not pressurize a flamable liquid with air.
Use a nitrogen tank or other inert gas.
Fuel + Oxygen + (heat of compression) = BOOM !
Static from the flow on an ungrounded item could be enough to set off quite a show.

Why not just wrap the end of the injector being tested with some kind of paper towel or sponge to capture the fluid in liquid form and try to remove the fog aspect. Using the fuel pump in the vehicle to provide the actual FP.
Then the fluid could run off the paper medium into a round container that can be calculated for volume over time.
Just thinking out loud again

 

This is a good idea. Except measure the weight change instead of volume. Heck, we're looking for #'s/hr, so go with weight instead of trying to convert from volume.

RBob.

 

if you take off the tbi might as well do some other testing too, How does this sound, make a little box out of some clear plexi glass to see how spacers affect the tbi spray patterns and at diffrent openings

 

I am not sure if you can use this info but .......


Have you guys heard of an Electronic Fule Injector Pulser? Mine is made by S&G Toolaid corp. It lets you fire each injector individually . At the following rates
1-400ms Pulses Simulates idle conditions
40-10ms pulses Simulates part throttle
100-4ms pulses Simulates WOT

These may be backwards ( its late )

..This way you would have a controlled amount of pulses . I payed $110.00 CDN for it . All you would need to do is give it a steady feed of fuel ...and a sealed place for it too squirt . Hioe it helps

 

The spray pattern gets affected by the air flowing into the engine on a TBI, so I doubt many conclusions can be drawn by watching them spray without an engine underneath it sucking air in (as far as seeing what effect spacers have at different throttle angles). A dyno would do the trick - both visually and power effects.

 

A guy I work with has one. Only difference is that his works in 5's instead of 4's (i.e. 1-500msec pulse, 10-50msec pulses, or 100-5msec pulses.) We use it to check spray patterns all the time, to help diagnose bad/clogged injectors.

 

Cool, just verified my injectors are 65lb/hr at 12psi. They're a lot more at 28psi . Thanks guys for the suggestions.

 

Sure you can pressurize with shop air. The dealers do it all the time when they clean fuel injectors on the car. They use a canister fuel injector cleaning system something like this picture.
I have one like it with adaptors for all cars and it works great. I made my money back doing the neighbors/friends cars.

 

So you actually flow tested them? How much where they at 28 psi? Did it follow teh ol' square root of the new pressure/old pressure? From the paper specs teh injectors look like they follow teh predicted change in flowrate quite well up to 45 psi at least.

 

mind posting your finding? what injectors do you have, the 5389?

 

Yeah, my TBI's all rebuilt and back together. I figure this would be the time to flow test em. Yesterday (as you know) I got the specs from Holley.
I couldn't adjust my fuel pressure below 28psi, I got 1.7lb/min which works out to around 100lb/hour. Take 100lb/hr * sqrt(12/28) = 65.5 lb/hr at 12psi. I didn't have a digital scale so I just used a digital bathroom scale . It was accurate to the tenth of a pound which supprised me, but not really. With the cost of todays electronics it makes sence they'd have a bathroom scale that accurate.

 

I didnt know you actually flow tested them. Real world data is always nice to have rather then some numbers from a tech rep.

I really hope Im having a pressure problem since those dont seem to go that far. Although thinking about it goautocenter rated my 350 at 265 hp. Figure its making around 245 net hp in the car and then the 65s just being able to keep up with it starts to make sense.

 

But how did you get the car into the bathroom? <ducking>

 

lol
Dim, the tbi pumps brand new are pathetic. I wouldn't be suprised if you're pump is the weak link. The only way to tell is to strap a gauge to the windshield and watch the pressure. If you've got the 265hp motor than I'd expect at least 255hp from it with the thirdgen exhaust and accessories.
Those injectors will support that level with little trouble. I'm seeing over 300hp right now with them at 28psi. I WAS running out of injector when I was running rather rich but it was still below 85% dc. Just replace the pump with a 190lph pump and don't worry about ti ever again. If you ever want some help let me know. Have you gone to any of the NJFBOA.org gatherings? I think we've met once but I'm terrible with names, faces, AND online handles.

 

I wouldnt be at all surprised if th pump is dropping down from teh stock pressure. If it can hold 12 psi through WOT Ill probably leave it for now. Im planning on some vortecs and maybe an XE262 flat tappet to get some of the lead out so Ill include a good pump at that time. I still have a 2 1/4" exaust so I have to factor that in. Going to get a welder at some point so I can fix taht problem.

I havnt made it to any of the meets. My POS only seems to work good for about a week at a time and I can count those on one hand with a few fingers missing.

Heh, names. I can barely remember my own name, let alone everyone elses.