2003 Santa Fe 2.7 Fuel Pressure check
 

Hi, working on a 2003 Santa Fe, AWD, 2.7L, has a low rpm miss, and some driveability issues. I'm leaning towards failing fuel pump, as the symptoms don't really change as the engine warms, which leads me to believe it's not a one of the ten cats. Anyway, I can't find anywhere to test the fuel pressure. No fuel filter, no schrader valve, and the only fuel line that comes apart so you could hook the gauge up to is is the return line, just tank side of the regulator. Do you need some kind of fancy adapter? Or am I on crack and missing something. I really don't want to spend 250 on a fuel pump and still be staring at the same problem with an empty wallet. Thanks for any help, I really appreciate it.

Scan first, low fuel pressure will not give a single cylinder misfire, it will be BLAAAAAH from not enough fuel to make power..

You can test pressure, just need the Hyundai adapter to tap into the pressure line.

Plugs (NGK Platinum or IRIDIUM) and a set of new wires will likely cure the problem if near orover 60,000 and never been replaced.

https://www.hyundaiforum.com/forum/a...1&d=1287593675

Thanks for the reply. It gives off a P0303 code. The Santa Fe has 185,000 on it, about 5k and six months ago I put on NGK plugs and new wires, air filter, pcv etc, it's been gradually getting worse since for about a year. I compression tested it and it came out good, can't remember for sure maybe 130 or so, so i bought a new injector for cyl 3. No change. I found the pressure tester adapter on otc's website, but don't really wanna spend 90 to use it once. I originally thought it was the upper cat on the rear bank, and the misfire was because the exhaust for cyl 3 went directly into the cat, and it was giving it too much backpressure. Just for giggles I replaced the upper o2 sensor in that cat, and no change. I'm down to either cats or fuel pressure. Since no 3 is almost at the end of the fuel rail, I figured it'd be succeptible to low pressure, but who knows.

Guessing at stuff gonna get expensive..

[SARCASM]

But not as expensive as it would be to take it to a STEALership mechanic to get it fixed properly.

[/SARCASM]

:rolleyes:

Thanks for all the input, it's much appreciated, as I don't have much experience with Hyundais.
I tried switching the wires and plugs.
I know I should have moved the injector too, but after I checked the compression and everything else seemed ok, I was relatively certain that was the problem.
I didn't switch the O2 sensors, I bought a new upper, I know they have never been changed, so they're overdue anyway.
The engine misses at idle, and is sluggish on take off, even just revving it up in park, and sometimes backfires/pre-ignites as you're taking off from a stop sign. It does reach highway speed, but it is short on power. Even under load around 3k, say going up a longer hill at 40mph, it'll stumble.

I'm not opposed to taking stuff to Mr. Hyundai, but at this point I'm only out 48.88 plus tax for the injector for stuff that wasn't overdue to be replaced anyway, and I enjoy the work.

And compunding your troubles so deep it will take somebody a good bit to unscrew what you did to make sure all the other stuff is ok before we can proceed with actual concern.

I guess I can put the original O2 sensor back in if that'll help. Otherwise, I'm here looking for advice from someone who knows more than I do. At this point my symptoms have not changed since I did any of the work, which leads me to believe I haven't f'd anything up.

I was able to rig up a gadget to check the fuel pressure at the pump, just using a male and female of a 3/8 quick disconnect and some 3/8 hose to my gauge. Pressure was 37psi running, 48 psi running with regulator disconnected. Seems to be in line with the specs that I've found.

Took the lower cat assembly loose, took it for a drive, same results. Standing under it with the exhaust removed it was obvious that the rear cylinder bank was the problem. There was an audible blip, blip here and there, which I'm guessing was cylinder 3 misfiring. Looking up at the internals of the upper cats as it was running was also notable. The internals of the front cat remained grey/white and looked normal, however the rear bank upper cat was glowing red, which I'm assuming means excess gas flowing through it? I guess I'll go back to the injector/spark plug/wire/compression. Any ideas, I'm all ears.

I gots a B1 cylinder head sitting at home if it comes to that ...

more likely loose pins at the injector plug than a bad injector
sometimes when the plenum gets lifted to change plugs the harness will get caught and pulled causing strain on connectors ,have a very close look at the connectors and find a small blade to insert in the connector to see if it is loose, should be a slight drag on it, i use a small cotter pin that i have hammered flat for this purpose

Poor technique... where's your proper pin fit gauges ? Just shoving homemade items and flat blades is good way to goof the connector if it was not goofed in the first place,, use the proper tool for the job.:)

At minimum, the rainbow test lead set can be used for pin fit testing

in response sbr711,
how exactly would YOU suggest to test a loose pin?
im willing to bet in the same fashion , well probably bigjdog does not have a hyundai test jumper (rainbow) such as me and you, in which case i thought the purpose of this forum was to help enable hyundai owners with there vehicles.
i am very sorry that my post to bigjdog has some how bothered you to the point that you feel it necassary to question my competence and "technique"
i personally don't see any problems with making a homemade tool if the result is in finding the repair to said vehicle, maybe your criticism should be more oriented at pointing out to bigjdog that it is possible to damage a connector by driving something to large into it (which to me is common sense) instead of a personal attack on my "technique"
cyber-bullys such as your self are why so many techs avoid forums such as this ,
and if your purpose was to create some attention to yourself and your great mechanical profess you certainly grabbed my attention with your comments

i have removed my post as not to offend ,

Good news!! Problem solved. First though, I have to admit that I never actually switched the plug wires from one cylinder to another, I just pulled them off the coil packs, and switched posts to make sure spark there, and that the idle changed when each wire was removed from the coil packs. Ends up the plug wires on cylinders 1 and 3 were melting from the inside out. The only reason I could tell was that there was a small section of the hard plastic part that just looked like the casting was bad when it was made, but since none of the others had any blemishes, i decided to try and disassemble it. Gave a tug on the wire and it came right out of the top. The coating was all melted and the wire just crumbled when I touched it. So I also pulled apart no. 1, same thing, just not quite as far along in the decay process. I was told the wires only had 10k or so on them, so I never gave them a second look until I had exhausted all other options. Long story longer, don't use Napa Mileage Plus wires on your 2.7. I got a set of NGK wires this time, so hopefully that'll be the last I have to mess with it. Thanks for the help guys, I really appreciate it.

Very good..

Normally I try to sell new wire set with plug replacement.. that way customer can decline the added expense, then I get paid to replace the wires at full price (wires and remove intake)..

Yeah, me too, you gotta take them halfway off anyway. This car is a neighbor's, who's kid is a friend of mine and he's the one who put the plugs and wires on. When it started having trouble I only changed the plug in cylinder 3, since that's where the trouble code pointed me. Guess I probably looked at the problem ten times, without knowing it was falling apart from the inside out.

The OE Hyundai wires will show a tell tale discolor ring on the black plastic stick that sits over the spark plug.. if real bad "ala" Accent & Elantra, they arc right throuch the plastic with age, see a dry black dusty lightning bolt zig zag crack, with white and white blue color too.. they're done, time for new wires and fresh plugs. See it too occassionally with the 2.7

Here are a couple of pics of the bad wire. After I pulled it apart, obviously.