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road test fuel pressure

Ok so I put the fuel pressure tester on and the first time I counted to almost 8 b4 it got to 30 psi, then I checked the fittings at motor and snugged them up a bit, turned key and press shot to 30 like fast. took vac hose off fpr, plugged hose of course, and got 40 psi. I couldn't rev it..i have a city cop living net to me and don't want to tick him off. I saw u said guys will make an extension and tape to windshield,lol, so I put gauge on top of fender with tape, shut hood on first latch and took a drive. got her up to 40, she kinda chugs a bit, fuel pressure stayed at 30 or 32 psi, so I hit it and she chugged then took off, no pops and fuel press went to 40 psi..my guess is fuel isn't the issue? when I hit her good she goes even if she hesitates and chugs some. the only 2 changes are the maf and the fuel filter, and the one foot of hose I had to put in. makes me wonder if the maf has issues at higher speeds? or something? I will be partly relieved if its not fuel pump cause I wasn't looking 4ward to dropping tank..lol
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Sounds like normal FPR behavior so yea, time to look elsewhere.

Might be worthwhile to use a real time obd2 reader to watch the o2 sensors to see if things go rich or lean when it stumbles so bad.
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Ive got one of those last week, the data was fine first day with a different maf sensor, then next day the maf reading lowered a bit and 02s started showing higher fuel trims. the stumbling started with newer maf. with old maf she culdnt idle good cold. then she would warm up and be fine..no stumbling up higher. but ran lean. I think this motor just doesn't like maf sensors..lol
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Fuel pressure looks good

Hesitation for any engine can be slow throttle fuel response
On carbs it meant accelerator pump was failing, not giving a full squirt of fuel when gas pedal was pushed down
That extra fuel was needed because Jets work on air flow and VACUUM
When you open the throttle plate air flow increases but vacuum drops, so there is a delay(hesitation) before Jets will supply enough fuel, that's why there is an Accelerator pump.

Fuel injection, of course, has no jets or an accelerator pump, so how does computer know to add more fuel quickly.........TPS, throttle position sensor.

TPS gives computer instant "heads up" to add more fuel, before MAF sees increase in air flow, before RPMs go up, TPS's sole purpose is to let computer know what the driver wants to do, speedup or slow down.
It is really the only Driver input engine sensor, serves no other purpose.
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Yep, this morning I had my lady drive so I could watch scanner, didn't see anything weird other than high fuel trims at times. had a trouble code but figured it was 0171 or 0174...then I checked it...walla...po0455...leak detected in evap system. she is finally talking to me. I actually put the valve on about 3 years ago but maybe a hose cracked or something...got to take down spare tire. btw..does anyone else have as much fun as me trying to sign onto this forum, love the forum but when I try to sign in and click on the bar the screen jumps down at least half way to bottom..?
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Ok so ive been trying to trouble shoot the evap system on the ranger and , lol, it may be leaking but its technically not getting vacuum anyway. when I did the swap there were things I was trying to fix and nothing else mattered. the control valve for evap is on driver inner fender, I followed the lines from the canister and gas tank to front to be sure of no breaks or cracks and they led me to the lil guy I wasn't sure what he was but I tought it was something 3.0 related, kinda is but it has a vacuum line on in that I taped up but if I had followed it , it might have gotten hooked up then. I'm guessing it needs manifold vacuum? so a trip to parts store for a vacuum tree which I hope they have, this may not fix the code but the evap needs hooked up anyways
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EVAP system sucks gas fumes from a gas tank.
On startup(once there is vacuum to use) the computer will open the EVAP solenoid a bit to apply vacuum to the charcoal canister and thru canister to the gas tank.
Computer will have a pressure sensor somewhere in the system, can be at canister end or gas tank end, they moved it around.
EVAP system hold negative pressure in the tank after engine is shut off, this is what causes that sucking noise when you unscrew the gas cap to fill up.
1995 and earlier Rangers usually didn't have EVAP self test, so no EVAP codes, 1996 and up did

The pressure sensor will tell computer of the change in pressure
Then computer closes EVAP solenoid and "watches" pressure
If the pressure changes then there is a Leak in the EVAP system
And you get an EVAP Code, which often includes "loose gas cap", lol, because that would be a Leak in the system.

Outside of a loose gas cap most EVAP codes are from cracked or broken filler tubes, the rubber just gets old.

From EVAP solenoid thru charcoal canister to gas tank and then gas cap there should be a sealed system.

You can remove hose from EVAP solenoid and suck or blow on it and it should hold/keep pressure.

You can do the same from the other end, remove gas cap put a short hose in the opening and wrap a rag around the hose.
Blow into the hose, should hold pressure
Do NOT use an air compressor for either test, you WILL blow off hoses, lung power only, so 2psi max.

You can often hear air escaping with this test if filler hose is the problem.

Last edited by RonD; 2 Weeks Ago at 12:04 PM.
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Lol, I got the vacuum hooked up to the purge valve , or at least that's what I think its called. its got a big hose from rear connected to its side then a similar one next to it but I cant remember what it was connected to on 3.0, its got a little bolt in it so it cant leak. so now the evap system has vacuum..lol. so your thinking my chugging or hesitation issue at about 40 has a better chance of being tps than evap leak? kinda makes sense because the tps tells ecu what I'm doing to throttle....my boss was right when he said last year that even if I get her to run it will be an ongoing thing....but at least she runs.
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My attempt to fix my lil mod for fuel return line in filler neck didn't work, she still drips if I put too much gas in her. the guy at summit told me he doesn't like that setup..he told me the right way to do it is the drop tank, take pump out, make a hole in tank near pump opening and put a fitting in tank..i guess like a quick connect, then a fitting on end of hose on return line, plug it in, done...is that how you would have done it?
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EVAP has nothing to do with engine operation.
Outside of using engine vacuum, so a vacuum leak in the hose from intake to EVAP Solenoid(or purge valve if that is first) could effect operation but just as a general vacuum leak.

A leak in the EVAP system itself, i.e. canister, hose to gas tank or in the gas tank, wouldn't effect operation of the engine
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Ok gotcha, I found a dual inlet, single outlet fuel filter for a explorer. plan to use that for return for fuel. cant take the drip in the filler neck. I did a voltage test on tps and it seems ok, but you never know? cant be a vacuum leak but that's what it feels like. ive never had a tps go bad so don't know what that could feel like, although ive read online that a bad tps can cause a lean code?
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Tps test

Ok, I did a test on tps...voltage rose steady from about 1 volt to 4.6 volts..shouldn't it go to 4.9?
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TPS should be .69 to .99 volt when throttle is closed, under 1 volt
And at WOT it should be at or above 4.5volts, 4.5 to 4.9 volts

TPS voltage is a Learned voltage, computer expects .69 to 4.9 range, and .99 to 4.5 is minimum range

You need to test TPS while it is connected, key on engine off
Use sewing pins to pierce and test wire voltages

Yes, steady voltage at any throttle position is what you want to see.
Try opening throttle 1/2 or 3/4 quickly make sure it responds quickly
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Tps test

Yep, that's how I tested it, key on motor off, lil nails in back of connecter. I didn't try the throttle half open thing...
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It should be fine then, but your problem is the hesitation from quick throttle movement so........
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Tps test

It's not so much quick throttle movement, it's any throttle movement once she gets into 3rd and cruising speed. From a dead stop hit her hard she jumps..under 30 she has *****, 3rd gear ***** disappear..lol. two things I keep thinking is 1) maybe the fuel pressure is ok bit volume not there? And 2) this started with the change of maf sensor. Although the other did it too, 4 maf have been on it. One from advanced, didn't like cold start but ran ok once warm. One from ebay, same when cold, ran like bear at first but then like crap. One from summit, ran so bad I sent it back, now this one from 2000 explorer , starts great, runs ok til she gets to cruising speed. If I tap pedal I can feel it bog down , if I git it hard it hesitates then takes off. Just got an odd feeling I'll b buying a new Ford one for 2000 explorer?
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Evan purge valve

Ok here's a question, on my evap purge valve it's got 2 big hoses on the one side, electrical plug on the other and an L vac fitting on bottom with skinny hard vac line...I put that to intake vac, the 2 big ones on the side..one goes back to tank, the other I can't remember what I took it off of on the old motor..you got any ideas?
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I have seen 3 port EVAP valves but can't picture connections, can you find an image online and link it here

Obviously one will go to intake and another to solenoid or canister

3rd could be reference vacuum???
Or just a vent
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Lol, in case its a vent I better unplug it, guess ill find out, thanks
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Ok, for anyone that needs this info...3 port evap purge valve..bottom big hose of course goes to tank, top big hose is fuel vapor goes to intake, under driver side is the port..mine had a hose with a bolt in it, bottom lil hose is vacuum feed for evap system. I got it together, drove it, seems better. ill find out in morning drive to work. 2 pending codes...running lean, egr insufficient flow..and egr can effect the performance as I have found out the hard way.
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Road test again

So with evap hooked up correctly, I think,, drove her to work and she did ok, once I was at road speed doing maybe 45 I was on a slight grade and gave it a Lil pedal..she bucked some so I hit it a Lil harder, she popped at me,lol, and she took off. When I was on steeper grade she bucked more so I kept her at about 50. I have 1 code now, insufficient flow, egr. No lean code? I felt dumb yesterday cause I had bought a tps. But she stumbles when I'm sitting still and hit gas hard, she has a hesitation, then if I hot it again she will Rev up so maybe the tps is starting to stick or something
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Egr issue

Most of the guys on the sites I'm looking at took care of the egr by eliminating it, what's your thoughts on that?
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Egr issue

Most of the guys on the sites I'm looking at took care of the egr by eliminating it, what's your thoughts on that?
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EGR slows air/fuel burn when engine is under a load.
Cylinder temps go up very high under load and that spikes NOx emissions, poisonous gas

EGR slows burn so cylinders don't get as hot, so lower NOx

Side benefit is that hotter cylinders also caused pinging/knocking under load because hotter temps caused Regular gas(87 octane) to self ignite

Engines with out EGR systems had to use a less aggressive spark timing to prevent pinging under load
EGR allowed a more aggressive spark timing

You can delete EGR but what I would do first is to Block EGR flow, and then drive engine a few days and see if you start to get pinging under load after engine is warmed up of course.
Just unplug vacuum hose on EGR valve and block its hose, EGR is now deleted

Most EGR deletes are/were done on engine that had distributors so you could adjust spark timing to stop the pinging
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Ya I did that back when I first got truck on road, egr stuck open so I pulled hose, drove it home and put new egr on. I did a vacuum test on it today, it passed. not sure what is causing the insufficient flow t/c? id rather fix the problem than delete egr. and the evap code is back, according to online the culprit is usually the vent solenoid on canister, I'm going to test both purge valve and vent sol 2moro I hope. thanks for your help
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