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| Oil pressure senders failing (Page 2/3) |
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olejoedad
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FEB 10, 11:01 AM
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The contacts for the fuel pump backup power circuit are stuck closed......
Time for another sending unit....
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tmadia
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FEB 10, 12:38 PM
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SunsetChaser
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MAR 10, 01:42 PM
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I'm reviving this thread hoping that a solution to this was ever found. I upgraded my 86 GT oil pressure sensor to the 88 sensor (per Ogre's instructions on his 88 oil sensor upgrade web page) and 3 of them have burned out on me in a matter of 3 months. Each one worked fine for 2-3 weeks and the oil gauge needle started fluttering before the unit finally quit.
Any follow up on this issue?
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Skybax
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MAR 10, 05:34 PM
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| quote | Originally posted by tmadia:
Today I got home from a short trip (in a different car) and when I walked by the Fiero I heard the buzzing of the fuel pump. The sender failed in such a way that the fuel pump was running continuously even without the key.
I'm guessing that's not caused by the gauge.
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That's a known problem reported in the past with the 1988 style oil psi sender, because basically they are a really crappy part. (yes even the AC Delco ones)
| quote | Originally posted by SunsetChaser:
I'm reviving this thread hoping that a solution to this was ever found. I upgraded my 86 GT oil pressure sensor to the 88 sensor (per Ogre's instructions on his 88 oil sensor upgrade web page) and 3 of them have burned out on me in a matter of 3 months. Each one worked fine for 2-3 weeks and the oil gauge needle started fluttering before the unit finally quit.
Any follow up on this issue? |
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That is also a known problem and why I don't recommend changing a 1985-87 oil psi switch to a 1988 style switch, you are better off just keeping the original 1985-87 style oil psi switch despite the "claims" of the 1988 oil psi switch being better, because the 1988 one is even MORE problematic in my opinion.
PS: Side note... Same can be said about the older 1985-87 SI alternator "upgrade" to newer style 1988 CS alternator, which isn't an upgrade at all when you honestly evaluate the totality of it all. Sure, it puts out a little more power if you are running a lot of aftermarket accessories and/or doing a ton of stop-n-go traffic or using at night, but older alternator is a much higher quality unit and better built product all around, and can handle the heat better. These "upgrades" are not a one-size-fits-all.
There is also a popular misconception in the "non-Fiero automotive community" that the 1988 Fiero is wonderful and the 1987 and older Fiero's are crap, lol. Sure, the 1988 suspension is much improved on, but there are disadvantages to the 88's (i.e. oil psi switch, alt, wheel bearings, master cylinder, elimination of coil/alt cooler, spindles, wheel choices, parts availability, costs, and so on). There are many advantages of owning a pre-1988 Fiero depending how you plan on using the car.[This message has been edited by Skybax (edited 03-10-2022).]
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theogre
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MAR 10, 06:03 PM
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Check the wiring again.
Where you got the senders?
Ebay Amazon and others have counterfeit problems.
E2A--->
Are you sure it really the sender?
When you pull a plug often it disturbs other things.
Dash gauge and wiring often have problems too and replacing old or new senders often won't help.
Put Ω meter on Pin A and base or anywhere on the engine block then run the engine.
Sender output 0 - 90Ω
But Good pressure should see ~ 40-45Ω[This message has been edited by theogre (edited 03-10-2022).]
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theogre
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MAR 10, 08:32 PM
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| quote | Originally posted by Skybax:
That is also a known problem and why I don't recommend changing a 1985-87 oil psi switch to a 1988 style switch, you are better off just keeping the original 1985-87 style oil psi switch despite the "claims" of the 1988 oil psi switch being better, because the 1988 one is even MORE problematic in my opinion.
PS: Side note... Same can be said about the older 1985-87 SI alternator "upgrade" to newer style 1988 CS alternator, which isn't an upgrade at all when you honestly evaluate the totality of it all. Sure, it puts out a little more power if you are running a lot of aftermarket accessories and/or doing a ton of stop-n-go traffic or using at night, but older alternator is a much higher quality unit and better built product all around, and can handle the heat better. These "upgrades" are not a one-size-fits-all.
There is also a popular misconception in the "non-Fiero automotive community" that the 1988 Fiero is wonderful and the 1987 and older Fiero's are crap, lol. Sure, the 1988 suspension is much improved on, but there are disadvantages to the 88's (i.e. oil psi switch, alt, wheel bearings, master cylinder, elimination of coil/alt cooler, spindles, wheel choices, parts availability, costs, and so on). There are many advantages of owning a pre-1988 Fiero depending how you plan on using the car. |
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When you upgrade sender to 88... If the sender dies, 88 won't dump oil on the road and Empty the pan quickly as old ones can and has done to many people. I have old ones fail doing just doing that enough time to know first hand. Just for my own car had to replace every 2-4 years w/ old one. Haven't replace 88 sender in 10+ years since upgrading...
If you find an old "gen1" unit to replace... often is very old stock or made in china or other 3rd world and diaphragm won't last. And that's senders even from known parts stores!
12SI is Good? No. SI Many Problems and Eats More Engine Power to Generate Less Amps at all points in the load curve.
I've replace many SI w/ F'd Diode Trio and more. Very few know why SI have the Infamous Diode Trio that dies and kills the battery fast. IOW When the Diode Trio fails, you hope to figure out fast, disconnect the battery and then call for a tow. If you don't you will replace the alt And often Battery too.
Unlike Most others including CS, when they die often can drive a lot with a dead alt and their not killing the battery at same time.
And doesn't mean battery is low... Bad Diode Trio and Gen1 HL motors w/ problems can drain the Battery to 0v and destroy it. As is, Starting Batteries do not like being drained below 10-11v w/o major shorting the lifetime.
And 88 Fiero isn't only one w/ CS alts. 87 Fiero 4cyl and other models had them first as part of killing off SI family.
New GM often still use CS complete or "CS" format cases and other parts but change the regulator and name and tied into PCM as well.
But will agree 88 has many problems... frame changes was good idea but bad execution and worse cancelled the car so many parts dried up 20+ years ago.
Just one big example was the front "hubs" that only 88 Fiero uses. Likely found another knuckle from another vehicle to fit "advance" suspension and made a custom hub to fit FWD/4WD knuckle.
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fierofool
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MAR 11, 09:08 AM
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tmadia, I have had the same repeated problems you have experienced. I've been through about 5 senders. They either blow the instrument panel fuse, or make the fuel pump continue to run. Even if they aren't bad right from the box, they fail in short order. I just got tired of the hassle and unplugged it and let the gauge peg full right. I even changed out my gauge set to no avail.
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SunsetChaser
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MAR 11, 10:44 AM
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I've checked the wiring. Initially I used the butt connectors that came with the pigtail but then I simply soldered the wires together and sealed them with heat shrink tubing.
The first sensor was from ebay, the second from walmart and the last one from Rock Auto. All 3 had the same failure rate.
Also I'm not sure if this is relevant but I should note that when the key is in accessory mode, the needle shows just above the red on the oil gauge (towards the left). It's only when I crank and start the engine that the needle is pegged far right until I shut the engine down. Maybe a clue as to how they might be failing?
| quote | Originally posted by theogre:
Check the wiring again.
Where you got the senders?
Ebay Amazon and others have counterfeit problems.
E2A--->
Are you sure it really the sender?
When you pull a plug often it disturbs other things.
Dash gauge and wiring often have problems too and replacing old or new senders often won't help.
Put Ω meter on Pin A and base or anywhere on the engine block then run the engine.
Sender output 0 - 90Ω
But Good pressure should see ~ 40-45Ω
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RWDPLZ
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MAR 11, 10:59 AM
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Crappy oil pressure sending units have been a problem in these cars for decades, they're probably all made by the same supplier that has been doing it wrong for a LONG time.
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Skybax
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MAR 14, 08:00 AM
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| quote | Originally posted by theogre:
12SI is Good? No. |
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Respectfully disagree, while the CS puts out more amps its not worth sacrificing all the Si good stuff, especially when a Fiero is stock with 99% daylight driving...
CS alternators produce a LOT more heat
They have a greater tendency to fry their bearings
Weak electrical components
Multiple plastic parts prone to failure
Integrated parts = disposable junk
Doesn't wear well
Si better cooling (more important on mid-engine)
Heavy duty construction
Better heat shield (more important on mid-engine)
Completely rebuildable with "quality parts"
Rectifier bridge can handle more heat
More mileage
If you put a CS and Si side-by-side, open them up, anyone can see the night & day difference. So if somebody wants to convert from Si to CS for more amps go for it, but nobody can claim its "better" because that is simply not true. The same can be said for switching from points & condenser to Petronix on a 60's car, sure its convenient and you never have to adjust it (lazy), but its a cheap POS and when it-fails it-fails, whereas a quality set of points & condenser are extremely reliable mechanical parts, will get you home even if they rarely malfunction, and can rev cleanly to 5500 rpm (my dual point dist on modified 289 can rev clean to 6500 rpm) and only need to adjust/set the dwell once a year. My original point was, an "upgrade" doesn't always result in "better" as claimed, its relative to risk evaluation, so I would rather use the originally designed 85-87 oil psi sender that works like a refrigerator for decades before leaking, than a 1988 pos oil psi sender that electrically malfunctions in a variety of ways.[This message has been edited by Skybax (edited 03-14-2022).]
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