I need to see if anyone can help me with this. I was going to work Friday and about half way there my 40 started bucking and hesitating. I could pull over and it would idle fine, as soon as I would get into 1st and start really putting it under a load it would just want to die. If I tried to push her more, she would backfire. Well, I got her back home and have gone through just everything I can imagine it would be, and some things that I found during my search here and on other sights. Timing is fine, TPS sensor good, IAC good, rotor does have a slight bit of marking around the center post area, but overall not bad. Drained some gas, looks fine, no sign of water. Not setting any codes right now, but was earlier setting a 44 (running lean). What I have found out is that after hooking up a fuel pressure gauge, it's steady at 11 psi while idling and drops to 9 if I just press the gas pedal while out of gear. Well this prompted me to take her out and observe the fuel pressure while driving. Immediatly, I noticed that upon reaching max rpm's in first and going into second the fuel pressure would go down below 5 psi. Not good, I know. Fuel pump is less than a month old and seems to be working fine. Fuel filter is good, as well as the lines. The Haynes manual says to check the oil pressure switch. Well first I don't even know where it is, or if I have one. I have a wiring harness by Centech with the diagnostic connector, but it dosn't have the G port to check to see if it is working right. My question is; can it be the fuel pump relay, the oil pressure swith, or something else that I've missed, and if so. How do I check these? Please, I've got to get this done, so all suggestions will be appreciated.:confused:

Just fired up my TBI for the first time today. :D

Anyway, back to your cruiser.
Have you checked the voltage at the fuel pump? does it have a good ground? If you have low voltage the new pump won't put out enough.
On a factory harness the oil pessure switch and the fuel pump relay are in parallel. This means each is supplying power to the fuel pump. I don't think these are your problem and many aftermarket harness' don't use the oil pressure sw. (if you have low voltage at pump DO check the voltage into and out of the relay)
Have you run a fuel volume check? You can carefully disconnect the fuel return line and let it go into a gas can, then start the engine. Should be able to get a quart of gas in about 30 seconds in the can.
Could you have gotten some dirty gas that has plugged up the gas filter?
Is your fuel injection filter on the high pressure side of the pump? The pump can push gas through the FI filter, but it cannot suck very efficiently :rolleyes:

How long have you been running your TBI??

I havn't checked the actual voltage to the pump. Ground is good. I just figured it's still whining fairly loudly while idling, must be good. I'll check that in the morning as well as do a volume check like you mentioned. Only filter I know is the factory stlyle inline FI filter that is between the pump and throttle body. Checked it, and it's clean. As was the gas. No water. I've been running her for about 4 months now. I did just recently find out though that the timing was way off. Finally found the EST wire that needed to be disconected prior to setting to 0 tdc. Upon fixing that, she ran great till this SH#T started.

The oil pressure switch on most set ups is just above the oil filter, treaded in to the block. The switch will have 2 or three wires coming from it. Loss of fuel pressure is the #1 failure for our FI engines. (I have a pressure gauge just off the hard line to the fuel rail.) The voltage issue is a great suggestion to look at. As for the relays they usually work or they don't, so I would look at other parts. Are you running a filter between the tank and the pump? If not the few months might have been enough for particles from the tank to get to it. An other thing could be debris in the tank clogging the pick up line so you don't get the volume of fuel you need when you get on it. Take you gas cap off, disconnect the pick up line from your pump and blast compressed air up the line to blow out the pick up. If this helps then you might want to drain and seal the tank. Bottom line is something is not letting you get the volume of fuel you need to the TB. What kind of shape are the injectors? If they are all cruddy they will not flow enough for the motor to perform, but this would be more of a gradual loss of performance, not all at once. Good luck!

BTW, my sister and brother in law are at Fort Polk. (Bio Chem) they called today and said they saw a great looking 40 the other day, if your rig is lifted crazy like it could have been yours! They said it had a TLCA.ORG sticker on it.

That would have been me then Mark. There are 3 FJ40's around here that I know of, and mine's the only lifted one. Tell em next time to flag down.
As for my fuel problem. Still no luck, solving it. I replaced all filters, checked the ground, and vented my tank. Still no luck. As for my injectors. I'm not too sure. Don't know what to compare them too. One does seem to be a bit more sporadic in it's spray. Is there any way to check them to be sure? I was told once I bought them, there's no returning them once installed. Anymore ideas? Any way to check to see if the fuel pump is dropping volume while under load?

One trick I learned was to look at the injector using a timing light. It strobes and "freezes" the gas droplets. You could tell if it is a nice complete cone pattern or if part is distorted indicating a blockage or deposit of some kind. You could compare yours with someone elses TBI as it is a simple test and non-invasive.

BUT, I don't think this is your problem. Restricted injectors are not going to cause low fuel pressure.

Around here, there are shops that have ultasonic injector cleaners (called an ASNU injector cleaner). The guy ar the shop near me checked (not cleaned) a set of injectors for a 3.0 toyota for $5 each. It showed me they were clean and funtioning OK. A full service of cleaning, new seals and caps runs about $30 each.
Doing the same on a TBI injector was about $55 each (more involved setup)

On your system, I suspect your flow is very low for some reason. At idle you are OK, but system drops when you try to demand more fuel.

What fuel pump are you using? (brand & model # if you have it)

Hmm in thinking about it Yoda is right the injectors would not drop the pressure, unless one stuck open. (You would smell that in a hurry) Does your motor have a regulator on it for the fuel pressure? My TPI unit has it on the back of the fuel rail; this just might be something else to look into. Other than that I would start looking directly at the pump. If I am correct you need something like 15 PSI for a TBI? You might hit the local pick an pull for a $5.00 - $15.00 inline pump to use as a test pump. If you have a regulator on the fuel syst. then grab a pump off a mid 80’s Volvo, Audie, or VW. Most of these cars have external pumps that put out 50-110 PSI. I am using a 1987 740 Turbo Volvo wagon pump and high pressure filter assembly. ($15.00) This combination puts out over 90 PSI and enough volume to power the TPI 383 with the hot chip. I just relay on the regulator to keep the pressure constant 34 PSI the engine (what my injectors where programmed at). Works great, and is cheep enough to keep a complete spare pump and new filter in the rig as a trail back up if needed. (I did by a new pump that is in the rig, $110 but with a life-time warrantee, the used one is now the back up. When I bought it the parts guy was trying to talk to me about how cool my 740 Turbo was…I just smiled and agreed with him:)

Just a cheep suggestion for trying a different fuel pump.

EDIT! If you do use a 50+ pump as a test pump check your hoses and fittings first for that kind of pressure! If you doubt they can handle it DONT try it at all! Your rig is much to valuable! I am using braided stainless air craft fuel lines and AN-6 fittings for all the high pressure stuff. I know you can use rubber hoses that are marked FI and hose clamps that are made for FI set ups, but check first!

It sounds like you have a bad pump. If its only a month old it should still be under warranty. Take it back and get another and replace the filter at the same time. (even if you just did)!

:confused: :confused: :confused:
Still no luck. I got all into my fuel system today. Drained and flushed the tank, there wasn't anything noticably wrong. Relocated the pump to sit flat and a bit closer to the tank. Replaced all filters including the ones on the injectors. And experimented with venting the tank. All to no avail. She will tease me and just haul ass for about a quarter of a mile then all of a sudden pressure takes a dive for zero. To get back home, I have to turn her off, builds up pressure, go about 100 feet, and start all over again. After a bit of doing that it almost didn't get back to 10 psi even while idling. My pump is a Holley Pro Jection universal in-line. Pre-set at 15 psi. Part #512-103 from Jegs where I ordered it. Hope they honor the warranty. Just bought it July 1st. Oh yea, I don't want to try and run a high volume pump with the lines I'm running. I'm using FI rubber lines all the way around. Just don't trust them and the hose clamps. As for regulators, only one is the factory one on top of the throttle body. Keep em coming guys. I'll get through this. I'm calling Jegs in the morning.

Just a wild thought. What happens if you clamp off the return line. In checking output pressure of the pump that was a test we used to do. If you block the return and there is still low pressure you have a bad pump!

Helocat: The presure reg is built into the throttle body. It is not adjustable, but there are replacement ones that are.

I'll try and do the clamping of the return line later today when I get back from work. I'll let you know how it goes.

I say it's your pump... I'd use a generic low-pressure filter BEFORE the pump... it keeps the crud out of the pump itself, which caused my last one to fail.

On my new one, it even said that if a filter was not used before the pump, the lifetime warranty is no good.

My pump is on the frame rail, so it gets GOOD gravity feed...the filter before it isn't an issue...

Have you tried the fuel flow test yet? I looked at Jegs page and this is the spec for the pump:

510-512-103 TBI Fuel Injection: 15 PSI; 190 LPH; 50 GPH; 300 PPH
MP Fuel Injection: 45 PSI; 132 LPH; 35 GPH; 210 PPH $109.99

Looks like it is not internally set for 15 psi (it just gives the flow rating for 15 PSI) as it also shows the flow at 45 PSI.

At that rating you should get a flow off the return line of about a quart in 20 seconds.

As a side note, Summit no longer carries this pump.

CRAP!! the photo looks like the pump I just installed in mine! (from NAPA) Mine was listed as a universal pump for a TBI system and there was a different # for an MPI system.

Top??
My other post didn't kick it up

I would like to thank everyone for there help. I found out last night that it was a pinched feed line coming out of the tank to the pump. :emb4: Thought I checked it once, but didn'nt find it till last night. Fixed that and it's running great. I did go ahead and buy another fuel pump though. It's a Master E2000, I'll keep it as a backup. I'm not running a resevoir right now, gonna see how it doe's without. If need be I'll hook one up. It's awesome the response that I got from everyone. Once again, THANKS.
:)

I was thinking about that posibility after pulling my seats today and seeing the pile of crap laying all around my fuel line.

The guy at customefis.com recommends this other master pump for these reasons:
02/15/02 - I now use a Master E2182 fuel pump. It has the same fuel pressure and flow capacity as the E2000, but with a 5/16" barb fitting on the outlet and a 1/2" barb fitting on the inlet, and costs $5 less. For about $3, I buy brass adapter fittings (in bulk) to convert the inlet and outlet to 3/8" barb fittings. This is a better way to attach the fuel lines than the E2000 Ford quick disconnect fittings.


Glad you got it going.